Performance counters

Use the metrics based on performance counters to measure and view the performance of storage systems and switches.

Overview

Performance counters are available for the following resources:

Volume counters
Disk counters
Storage system and switch port counters

Volume counters

Volume performance counters are divided into the following categories:

Volume I/O counters
Volume cache hit counters
Volume data counters
Volume service time counters
Volume cache counters
Volume miscellaneous counters
Volume special computed values

Table 1. Volume I/O counters
Counter	Counter type	Resource or component type	Description
Read I/O Count (normal)	001	DS8000: volume, array, controller, storage system	Number of input/output (I/O) operations for nonsequential read requests, for a particular component over a particular time interval.
Read I/O Count (sequential)	002	DS8000: volume, array, controller, storage system	Number of I/O operations for sequential read requests, for a particular component over a particular time interval.
Read I/O Count (overall)	003	IBM Storage Virtualize: volume, node, I/O group, pool, storage system SMI-S BSP: volume, controller, storage system XIV®: volume, module, storage system	Number of I/O operations for all read requests, for a particular component over a particular time interval.
Write I/O Count (normal)	004	DS8000: volume, array, controller, storage system	Number of I/O operations for nonsequential write requests, for a particular component over a particular time interval.
Write I/O Count (sequential)	005	DS8000: volume, array, controller, storage system	Number of I/O operations for sequential write requests, for a particular component over a particular time interval.
Write I/O Count (overall)	006	IBM Storage Virtualize: volume, node, I/O group, pool, storage system SMI-S BSP: volume, controller, storage system XIV: volume, module, storage system	Number of I/O operations for all write requests, for a particular component over a particular time interval.
Total I/O Count (overall)	009	SMI-S BSP: volume, controller, storage system	Total number of I/O operations for all read and write requests, both sequential and nonsequential, for a particular component over a particular time interval.
Read Track Count	062	IBM Storage Virtualize: volume, node, I/O group, storage system	Number of cache track read operations, for a particular component over a particular time interval.
Write Track Count	063	IBM Storage Virtualize: volume, node, I/O group, storage system	Number of cache track write operations, for a particular component over a particular time interval.
Fast Write Mode Track Count	065	IBM Storage Virtualize: volume, node, I/O group, storage system	Number of tracks writes that were processed in fast-write write mode, for a particular component over a particular time interval. Included as part of the “Write Track Count”.
Write Through Mode Track Count	066	IBM Storage Virtualize: volume, node, I/O group, storage system	Number of tracks writes that were processed in write-through write mode, for a particular component over a particular time interval. Included as part of the “Write Track Count”.
Flush Through Mode Track Count	067	IBM Storage Virtualize: volume, node, I/O group, storage system	Number of tracks writes that were processed in flush-through write mode, for a particular component over a particular time interval. Included as part of the “Write Track Count”.
Cache Overflow Mode Track Count	068	IBM Storage Virtualize: volume, node, I/O group, storage system	Number of tracks writes that were processed in cache overflow write mode, for a particular component over a particular time interval. Included as part of the “Write Track Count”.
Global Mirror Write Count	090	IBM Storage Virtualize: volume, node, I/O group, storage system	Number of write operations issued to the secondary site for Global Mirror, for a particular component over a particular time interval.
Global Mirror Overlapping Write Count	091	IBM Storage Virtualize: volume, node, I/O group, storage system	Number of serialized overlapping write operations encountered at the primary site for Global Mirror, for a particular component over a particular time interval.
HPF Read I/O Count	093	DS8000: volume, array, controller, storage system	Number of read I/O operations (both normal and sequential) that were issued using the High Performance FICON® (HPF) feature of the storage system, for a particular component over a particular time interval.
HPF Write I/O Count	094	DS8000: volume, array, controller, storage system	Number of write I/O operations (both normal and sequential) that were issued using the High Performance FICON (HPF) feature of the storage system, for a particular component over a particular time interval.
Non-Preferred Node I/O Count	096	IBM Storage Virtualize: I/O group, volume	Number of I/O operations (both read and write) that were performed using the non-preferred nodes of the volumes. This value is a subset of the total I/O operations for the component, and is normally expected to be 0.
Maintenance Operations Count	098	BSP: volume, controller, storage system	Cumulative count of all disk maintenance operations (SCSI commands such as: Verify, skip-mask, XOR read, XOR write-read, and so on). This value is required to understand the load on the component that might interfere with normal read and write operations.
Read Hit I/O Percentage for Small Transfers	104	XIV: volume, module, storage system	Percentage of I/O read operations over a specified interval that resulted in cache hits. Applies to data transfers that are ≤ 8 KB.
Read Hit I/O Percentage for Medium Transfers	105	XIV: volume, module, storage system	Percentage of I/O read operations over a specified interval that resulted in cache hits. Applies to data transfers that are > 8 KB and ≤ 64 KB.
Read Hit I/O Percentage for Large Transfers	106	XIV: volume, module, storage system	Percentage of I/O read operations over a specified interval that resulted in cache hits. Applies to data transfers that are > 64 KB and ≤ 512 KB.
Read Hit I/O Percentage for Huge Transfers	107	XIV: volume, module, storage system	Percentage of I/O read operations over a specified interval that resulted in cache hits. Applies to data transfers that are > 512 KB.
Read Miss I/O Percentage for Small Transfers	108	XIV: volume, module, storage system	Percentage of I/O read operations over a specified interval that resulted in cache misses. Applies to data transfers that are ≤ 8 KB.
Read Miss I/O Percentage for Medium Transfers	109	XIV: volume, module, storage system	Percentage of I/O read operations over a specified interval that resulted in cache misses. Applies to data transfers that are > 8 KB and ≤ 64 KB.
Read Miss I/O Percentage for Large Transfers	110	XIV: volume, module, storage system	Percentage of I/O read operations over a specified interval that resulted in cache misses. Applies to data transfers that are > 64 KB and ≤ 512 KB.
Read Miss I/O Percentage for Huge Transfers	111	XIV: volume, module, storage system	Percentage of I/O read operations over a specified interval that resulted in cache misses. Applies to data transfers that are > 512 KB.
Write Hit I/O Percentage for Small Transfers	112	XIV: volume, module, storage system	Percentage of I/O write operations over a specified interval that resulted in cache hits. Applies to data transfers that are ≤ 8 KB.
Write Hit I/O Percentage for Medium Transfers	113	XIV: volume, module, storage system	Percentage of I/O write operations over a specified interval that resulted in cache hits. Applies to data transfers that are > 8 KB and ≤ 64 KB.
Write Hit I/O Percentage for Large Transfers	114	XIV: volume, module, storage system	Percentage of I/O write operations over a specified interval that resulted in cache hits. Applies to data transfers that are > 64 KB and ≤ 512 KB.
Write Hit I/O Percentage for Huge Transfers	115	XIV: volume, module, storage system	Percentage of I/O write operations over a specified interval that resulted in cache hits. Applies to data transfers that are > 512 KB.
Write Miss I/O Percentage for Small Transfers	116	XIV: volume, module, storage system	Percentage of I/O write operations over a specified interval that resulted in cache misses. Applies to data transfers that are ≤ 8 KB.
Write Miss I/O Percentage for Medium Transfers	117	XIV: volume, module, storage system	Percentage of I/O write operations over a specified interval that resulted in cache misses. Applies to data transfers that are > 8 KB and ≤ 64 KB.
Write Miss I/O Percentage for Large Transfers	118	XIV: volume, module, storage system	Percentage of I/O write operations over a specified interval that resulted in cache misses. Applies to data transfers that are > 64 KB and ≤ 512 KB.
Write Miss I/O Percentage for Huge Transfers	119	XIV: volume, module, storage system	Percentage of I/O write operations over a specified interval that resulted in cache misses. Applies to data transfers that are > 512 KB.
Read SSD Hit Percentage for Small Transfer Sizes	153	XIV: volume, pool, module, host connection, storage system	Percentage of read operations over a specified time interval that accessed SSD cache memory. Applies to data transfers that are ≤ 8 KB.
Read SSD Hit Percentage for Medium Transfer Sizes	154	XIV: volume, pool, module, host connection, storage system	Percentage of read operations over a specified time interval that accessed SSD cache memory. Applies to data transfers that are > 8 KB and ≤ 64 KB.
Read SSD Hit Percentage for Large Transfer Sizes	155	XIV: volume, pool, module, host connection, storage system	Percentage of read operations over a specified time interval that accessed SSD cache memory. Applies to data transfers that are > 64 KB and ≤ 512 KB.
Read SSD Hit Percentage for Huge Transfer Sizes	156	XIV: volume, pool, module, host connection, storage system	Percentage of read operations over a specified time interval that accessed SSD cache memory. Applies to data transfers that are > 512 KB.
Unaligned Write I/O Count	180	IBM Storage Virtualize²: node, I/O group, host connection, storage system	The number of write operations that are not aligned on a boundary between 4 KB physical blocks. Unaligned write operations can cause a significant decrease in efficiency of write operations to some types of back-end disks. You can ignore this counter for iSeries servers.
Compressed Volumes I/O Count	182	IBM Storage Virtualize: node, I/O group, storage system	The total number of all read and write operations for compressed volumes.
Cache Read I/O Count - Volume Cache	610	IBM Storage Virtualize¹: volume, pool, node, I/O group, host connection, storage system	The number of read I/Os measured at the volume cache, which includes host reads as well as reads needed for remote replication.
Cache Read I/O Count - Volume Copy Cache	609	IBM Storage Virtualize¹: volume, pool, node, I/O group, host connection, storage system	The number of read I/Os measured at the volume copy cache, which includes host reads as well as reads needed for replication and other internal processing.
Cache Write I/O Count - Volume Cache	612	IBM Storage Virtualize¹: volume, pool, node, I/O group, host connection, storage system	The number of write I/Os measured at the volume cache, which includes host writes as well as writes needed for remote replication.
Cache Write I/O Count - Volume Copy Cache	611	IBM Storage Virtualize¹: volume, pool, node, I/O group, host connection, storage system	The number of write I/Os measured at the volume copy cache, which includes host writes as well as writes needed for replication and other internal processing.
Cache Prestage I/O Count - Volume Copy Cache	613	IBM Storage Virtualize¹: volume, pool, node, I/O group, host connection, storage system	The number of prefetch disk-to-cache transfer operations that are processed in the volume copy cache.
Cache Stage I/O Count - Volume Cache	615	IBM Storage Virtualize¹: volume, pool, node, I/O group, host connection, storage system	The number of disk-to-cache transfer operations that are processed in the volume cache.
Cache Stage I/O Count - Volume Copy Cache	614	IBM Storage Virtualize¹: volume, pool, node, I/O group, host connection, storage system	The number of disk-to-cache transfer operations that are not prefetch operations and are processed in the volume copy cache.
Cache Destage I/O Count - Volume Cache	617	IBM Storage Virtualize¹: volume, pool, node, I/O group, host connection, storage system	The number of cache-to-disk transfer operations that are processed in the volume cache.
Cache Destage I/O Count - Volume Copy Cache	616	IBM Storage Virtualize¹: volume, pool, node, I/O group, host connection, storage system	The number of cache-to-disk transfer operations that are processed in the volume copy cache.
In-flight I/O Count	658	IBM Storage Virtualize¹: managed disk	The actual number of concurrent operations that are issued from the cache to the managed disk. The number of in-flight operations cannot exceed the target, but also varies over time, depending on the type of I/O operations and on the performance of the managed disk.
Target I/O Count	657	IBM Storage Virtualize¹: managed disk	The maximum number of concurrent operations that can be issued from the cache to the managed disk. This target changes over time, depending on changes in cache utilization and on changes in the performance of the managed disk.
Notes: This counter is only available for resources that are running IBM Storage Virtualize 7.3 or later. This counter is only available for resources that are running IBM Storage Virtualize 7.4 or later.

Table 2. Volume cache hit counters
Counter	Counter type	Resource or component type	Description
Read Cache Hits (normal)	010	DS8000: volume, array, controller, storage system	Number of cache hits for nonsequential read requests, for a particular component over a particular time interval.
Read Cache Hits (sequential)	011	DS8000: volume, array, controller, storage system	Number of cache hits for sequential read requests, for a particular component over a particular time interval.
Read Cache Hits (overall)	012	SMI-S BSP: volume, controller, storage system XIV: volume, module, storage system	Number of cache hits for all read requests, for a particular component over a particular time interval.
Write Cache Hits (normal)	013	DS8000: volume, array, controller, storage system	Number of cache hits for nonsequential write requests, for a particular component over a particular time interval.
Write Cache Hits (sequential)	014	DS8000: volume, array, controller, storage system	Number of cache hits for sequential write requests, for a particular component over a particular time interval.
Write Cache Hits (overall)	015	SMI-S BSP: volume, controller, storage system XIV: volume, module, storage system	Number of cache hits for all write requests, for a particular component over a particular time interval.
Read Tracks Cache Hits	069	IBM Storage Virtualize: volume, node, I/O group, storage system	Number of read track cache hits that were entirely serviced from prestaged or non-prestaged tracks for a particular component over a particular time interval.
Read Track Cache Hits Sector Count	070	IBM Storage Virtualize: node	Number of sectors read for cache hits that were entirely serviced from prestaged or non-prestaged tracks for a particular component over a particular time interval.
Read Sector Cache Hits - Volume Cache	69	IBM Storage Virtualize: volume, pool, node, I/O group, host connection, storage system	The number of cache sectors or tracks that achieved read cache hits in the volume cache. For resources that are running a version of IBM Storage Virtualize that is earlier than 7.3, the unit of the counter is tracks.
Read Sector Cache Hits - Volume Copy Cache	607	IBM Storage Virtualize¹: volume, pool, node, I/O group, host connection, storage system	The number of cache sectors that achieved read cache hits in the volume copy cache.
Prestage Cache Hits	80	IBM Storage Virtualize: volume, pool, node, I/O group, host connection, storage system	The number of prefetched cache sectors or tracks that achieved read cache hits in the volume copy cache. For resources that are running a version of IBM Storage Virtualize that is earlier than 7.3, the unit of the counter is tracks.
Destage Cache Hits - Volume Cache	81	IBM Storage Virtualize¹: volume, pool, node, I/O group, host connection, storage system	The number of destaged cache sectors or tracks that achieved write cache hits in the volume cache. That is, the number of writes that modified only data that was already marked "dirty" in the cache. For resources that are running a version of IBM Storage Virtualize that is earlier than 7.3, the unit of the counter is tracks.
Destage Cache Hits - Volume Copy Cache	608	IBM Storage Virtualize¹: volume, pool, node, I/O group, host connection, storage system	The number of destaged cache sectors that achieved write cache hits in the volume copy cache. That is, the number of writes that modified only data that was already marked "dirty" in the cache.
Note: This counter is only available for resources that are running IBM Storage Virtualize 7.3 or later.

Table 3. Volume data counters
Counter	Counter type	Resource or component type	Description
Read KB Count	019	IBM Storage Virtualize: volume, node, I/O group, pool, storage system SMI-S BSP: volume, controller, storage system XIV: volume, module, storage system	Number of KB (2^10 bytes) of data transferred for read operations, for a particular component over a particular time interval.
Write KB Count	020	IBM Storage Virtualize: volume, node, I/O group, pool, storage system SMI-S BSP: volume, controller, storage system XIV: volume, module, storage system	Number of KB (2^10 bytes) of data transferred for write operations, for a particular component over a particular time interval.
Total KB Count	021	SMI-S BSP: volume, controller, storage system	Total number of KB (2^10 bytes) of data transferred for read and write operations, for a particular component over a particular time interval.
Read Data Count	022	DS8000: volume, array, controller, storage system	Number of 128 KB chunks (128*2^10 bytes) of data transferred for read operations, for a particular component over a particular time interval.
Write Data Count	023	DS8000: volume, array, controller, storage system	Number of 128 KB chunks (128*2^10 bytes) of data transferred for write operations, for a particular component over a particular time interval.
Read Sector Count	071	IBM Storage Virtualize: node	Number of cache sectors read, for a particular component over a particular time interval.
Write Sector Count	072	IBM Storage Virtualize: node	Number of cache sectors written, for a particular component over a particular time interval.
Fast Write Mode Sector Count	074	IBM Storage Virtualize: node	Number of written cache sectors processed in fast-write write mode, for a particular component over a particular time interval. Included as part of the “Write Sector Count”.
Write Through Mode Sector Count	075	IBM Storage Virtualize: node	Number of written cache sectors processed in write-through write mode, for a particular component over a particular time interval. Included as part of the “Write Sector Count”.
Flush Through Mode Sector Count	076	IBM Storage Virtualize: node	Number of written cache sectors processed in flush-through write mode, for a particular component over a particular time interval. Included as part of the “Write Sector Count”.
Cache Overflow Mode Sector Count	077	IBM Storage Virtualize: node	Number of written cache sectors processed in cache overflow write mode, for a particular component over a particular time interval. Included as part of the “Write Sector Count”.
Non-Preferred Node KB Count	097	IBM Storage Virtualize: I/O group, volume	Number of KB (both read and write) that were transferred using the non-preferred nodes of the volumes. This value is a subset of the total KB transferred for the component, and is normally expected to be 0.
Read Hit KB Percentage for Small Transfers	120	XIV: volume, module, storage system	Percentage of KB of data that is transferred over a specified interval because of read operations that resulted in cache hits. Applies to data transfers ≤ 8 KB.
Read Hit KB Percentage for Medium Transfers	121	XIV: volume, module, storage system	Percentage of KB of data that is transferred over a specified interval because of read operations that resulted in cache hits. Applies to data transfers > 8 KB and ≤ 64 KB.
Read Hit KB Percentage for Large Transfers	122	XIV: volume, module, storage system	Percentage of KB of data that is transferred over a specified interval because of read operations that resulted in cache hits. Applies to data transfers > 64 KB and ≤ 512 KB.
Read Hit KB Percentage for Huge Transfers	123	XIV: volume, module, storage system	Percentage of KB of data that is transferred over a specified interval because of read operations that resulted in cache hits. Applies to data transfers > 512 KB.
Read Miss KB Percentage for Small Transfers	124	XIV: volume, module, storage system	Percentage of KB of data that is transferred over a specified interval because of read operations that resulted in cache misses. Applies to data transfers ≤ 8 KB.
Read Miss KB Percentage for Medium Transfers	125	XIV: volume, module, storage system	Percentage of KB of data that is transferred over a specified interval because of read operations that resulted in cache misses. Applies to data transfers > 8 KB and ≤ 64 KB.
Read Miss KB Percentage for Large Transfers	126	XIV: volume, module, storage system	Percentage of KB of data that is transferred over a specified interval because of read operations that resulted in cache misses. Applies to data transfers > 64 KB and ≤ 512 KB.
Read Miss KB Percentage for Huge Transfers	127	XIV: volume, module, storage system	Percentage of KB of data that is transferred over a specified interval because of read operations that resulted in cache misses. Applies to data transfers > 512 KB.
Write Hit KB Percentage for Small Transfers	128	XIV: volume, module, storage system	Percentage of KB of data that is transferred over a specified interval because of write operations that resulted in cache hits. Applies to data transfers ≤ 8 KB.
Write Hit KB Percentage for Medium Transfers	129	XIV: volume, module, storage system	Percentage of KB of data that is transferred over a specified interval because of write operations that resulted in cache hits. Applies to data transfers > 8 KB and ≤ 64 KB.
Write Hit KB Percentage for Large Transfers	130	XIV: volume, module, storage system	Percentage of KB of data that is transferred over a specified interval because of write operations that resulted in cache hits. Applies to data transfers > 64 KB and ≤ 512 KB.
Write Hit KB Percentage for Huge Transfers	131	XIV: volume, module, storage system	Percentage of KB of data that is transferred over a specified interval because of write operations that resulted in cache hits. Applies to data transfers > 512 KB.
Write Miss KB Percentage for Small Transfers	132	XIV: volume, module, storage system	Percentage of KB of data that is transferred over a specified interval because of write operations that resulted in cache misses. Applies to data transfers ≤ 8 KB.
Write Miss KB Percentage for Medium Transfers	133	XIV: volume, module, storage system	Percentage of KB of data that is transferred over a specified interval because of write operations that resulted in cache misses. Applies to data transfers > 8 KB and ≤ 64 KB.
Write Miss KB Percentage for Large Transfers	134	XIV: volume, module, storage system	Percentage of KB of data that is transferred over a specified interval because of write operations that resulted in cache misses. Applies to data transfers > 64 KB and ≤ 512 KB.
Write Miss KB Percentage for Huge Transfers	135	XIV: volume, module, storage system	Percentage of KB of data that is transferred over a specified interval because of write operations that resulted in cache misses. Applies to data transfers > 512 KB.
Read SSD Data Hit Percentage for Small Transfer Sizes	157	XIV: volume, pool, module, host connection, storage system	Percentage of data transfers over a specified time interval that accessed SSD cache memory. Applies to data transfers ≤ 8 KB.
Read SSD Data Hit Percentage for Medium Transfer Sizes	158	XIV: volume, pool, module, host connection, storage system	Percentage of data transfers over a specified time interval that accessed SSD cache memory. Applies to data transfers > 8 KB and ≤ 64 KB.
Read SSD Data Hit Percentage for Large Transfer Sizes	159	XIV: volume, pool, module, host connection, storage system	Percentage of data transfers over a specified time interval that accessed SSD cache memory. Applies to data transfers > 64 KB and ≤ 512 KB.
Read SSD Data Hit Percentage for Huge Transfer Sizes	160	XIV: volume, pool, module, host connection, storage system	Percentage of data transfers over a specified time interval that accessed SSD cache memory. Applies to data transfers > 512 KB.
Compressed Volumes KB Count	183	IBM Storage Virtualize: node, I/O group, storage system	The total number of KiB that were read from or written to compressed volumes.

Table 4. Volume service time counters
Counter	Counter type	Resource or component type	Description
Read Service Time	025	IBM Storage Virtualize: volume, node, I/O group, pool, storage system XIV: volume, module, storage system	Number of milliseconds that it took to service all read operations, for a particular component over a particular time interval.
Write Service Time	026	IBM Storage Virtualize: volume, node, I/O group, pool, storage system XIV: volume, module, storage system	Number of milliseconds that it took to service all write operations, for a particular component over a particular time interval.
Read Service Periods	028	DS8000: volume, array, controller, storage system SMI-S BSP: volume, controller, storage system	Number of time periods that it took to service all read operations, for a particular component over a particular time interval. The exact time interval length is device-dependent, but is typically 16 milliseconds for DS devices.
Write Service Periods	029	DS8000: volume, array, controller, storage system SMI-S BSP: volume, controller, storage system	Number of time periods that it took to service all write operations, for a particular component over a particular time interval. The exact time interval length is device-dependent, but is typically 16 milliseconds for DS devices.
Overall Service Periods	030	SMI-S BSP: volume, controller, storage system	Total number of time periods that it took to service all I/O operations (read and write), for a particular component over a particular time interval. The exact time interval length is device-dependent, but is typically 16 milliseconds for DS devices.
Peak Read Response Time	088	IBM Storage Virtualize: volume, node, I/O group, storage system	The peak (worst) response time for disk reads for a particular component over a particular time interval. Value in microseconds.
Peak Write Response Time	089	IBM Storage Virtualize: volume, node, I/O group, storage system	The peak (worst) response time for disk writes for a particular component over a particular time interval. Value in microseconds.
Global Mirror Service Time	092	IBM Storage Virtualize: volume, node, I/O group, storage system	Number of additional milliseconds it took to service all secondary write operations for Global Mirror, beyond the time required to service the primary writes, for a particular component over a particular time interval.
Overall Host Attributed Service Time	095	IBM Storage Virtualize: volume, node, I/O group, storage system	Cumulative transfer latency, in microseconds, coalesced for both reads and writes excluding any status-only transfers. This value is the time taken for hosts to respond to transfer-ready notifications from the nodes (for read) and the time taken for hosts to send the write data after receiving transfer-ready notification from the nodes (for write). This value is provided as an aid to diagnose slow hosts and poorly performing fabrics.
Read Cache Hit Service Periods	099	BSP: volume, controller, storage system	Number of time periods that it took to service all read cache hit operations, for a particular component over a particular time interval. The exact time interval length is device-dependent.
Write Cache Hit Service Periods	100	BSP: volume, controller, storage system	Number of time periods that it took to service all write cache hit operations, for a particular component over a particular time interval. The exact time interval length is device-dependent.
Idle Periods	102	BSP: volume, storage system	The number of time periods during which the component was idle. The exact time interval length is device-dependent.
Maintenance Service Periods	103	BSP: volume, controller, storage system	Number of time periods it took to service all disk maintenance operations, for a particular component over a particular time interval. The exact time interval length is device-dependent.
Read Hit Time Percentage for Small Transfers	136	XIV: volume, module, storage system	Percentage of service time, over a specified interval, that was spent on read operations that resulted in cache hits. Applies to data transfers ≤ 8 KB.
Read Hit Time Percentage for Medium Transfers	137	XIV: volume, module, storage system	Percentage of service time, over a specified interval, that was spent on read operations that resulted in cache hits. Applies to data transfers > 8 KB and ≤ 64 KB.
Read Hit Time Percentage for Large Transfers	138	XIV: volume, module, storage system	Percentage of service time, over a specified interval, that was spent on read operations that resulted in cache hits. Applies to data transfers > 64 KB and ≤ 512 KB.
Read Hit Time Percentage for Huge Transfers	139	XIV: volume, module, storage system	Percentage of service time, over a specified interval, that was spent on read operations that resulted in cache hits. Applies to data transfers > 512 KB.
Read Miss Time Percentage for Small Transfers	140	XIV: volume, module, storage system	Percentage of service time, over a specified interval, that was spent on read operations that resulted in cache misses. Applies to data transfers ≤ 8 KB.
Read Miss Time Percentage for Medium Transfers	141	XIV: volume, module, storage system	Percentage of service time, over a specified interval, that was spent on read operations that resulted in cache misses. Applies to data transfers > 8 KB and ≤ 64 KB.
Read Miss Time Percentage for Large Transfers	142	XIV: volume, module, storage system	Percentage of service time, over a specified interval, that was spent on read operations that resulted in cache misses. Applies to data transfers > 64 KB and ≤ 512 KB.
Read Miss Time Percentage for Huge Transfers	143	XIV: volume, module, storage system	Percentage of service time, over a specified interval, that was spent on read operations that resulted in cache misses. Applies to data transfers > 512 KB.
Write Hit Time Percentage for Small Transfers	144	XIV: volume, module, storage system	Percentage of service time, over a specified interval, that was spent on write operations that resulted in cache hits. Applies to data transfers ≤ 8 KB.
Write Hit Time Percentage for Medium Transfers	145	XIV: volume, module, storage system	Percentage of service time, over a specified interval, that was spent on write operations that resulted in cache hits. Applies to data transfers > 8 KB and ≤ 64 KB.
Write Hit Time Percentage for Large Transfers	146	XIV: volume, module, storage system	Percentage of service time, over a specified interval, that was spent on write operations that resulted in cache hits. Applies to data transfers > 64 KB and ≤ 512 KB.
Write Hit Time Percentage for Huge Transfers	147	XIV: volume, module, storage system	Percentage of service time, over a specified interval, that was spent on write operations that resulted in cache hits. Applies to data transfers > 512 KB.
Write Miss Time Percentage for Small Transfers	148	XIV: volume, module, storage system	Percentage of service time, over a specified interval, that was spent on write operations that resulted in cache misses. Applies to data transfers ≤ 8 KB.
Write Miss Time Percentage for Medium Transfers	149	XIV: volume, module, storage system	Percentage of service time, over a specified interval, that was spent on write operations that resulted in cache misses. Applies to data transfers > 8 KB and ≤ 64 KB.
Write Miss Time Percentage for Large Transfers	150	XIV: volume, module, storage system	Percentage of service time, over a specified interval, that was spent on write operations that resulted in cache misses. Applies to data transfers > 64 KB and ≤ 512 KB.
Write Miss Time Percentage for Huge Transfers	151	XIV: volume, module, storage system	Percentage of service time, over a specified interval, that was spent on write operations that resulted in cache misses. Applies to data transfers > 512 KB.
Read SSD Response Time for Small Transfer Sizes	161	XIV: volume, pool, module, host connection, storage system	Average number of milliseconds that was required to service each hit operation of SSD read memory over a specified time interval. Applies to transfer operations ≤ 8 KB.
Read SSD Response Time for Medium Transfer Sizes	162	XIV: volume, pool, module, host connection, storage system	Average number of milliseconds that was required to service each hit operation of SSD read memory over a specified time interval. Applies to transfer operations > 8 KB and ≤ 64 KB.
Read SSD Response Time for Large Transfer Sizes	163	XIV: volume, pool, module, host connection, storage system	Average number of milliseconds that was required to service each hit operation of SSD read memory over a specified time interval. Applies to transfer operations > 64 KB and ≤ 512 KB.
Read SSD Response Time for Huge Transfer Sizes	164	XIV: volume, pool, module, host connection, storage system	Average number of milliseconds that was required to service each hit operation of SSD read memory over a specified time interval. Applies to transfer operations > 512 KB.
Compressed Volumes Service Time	184	IBM Storage Virtualize: node, I/O group, storage system	The total number of milliseconds that it took to service all read and write operations for compressed volumes.
Cache Prestage Service Time - Volume Cache	618	IBM Storage Virtualize¹: volume, pool, node, I/O group, host connection, storage system	The number of milliseconds that it took to service all prestage I/Os measured at the volume copy cache.
Cache Stage Service Time - Volume Cache	620	IBM Storage Virtualize¹: volume, pool, node, I/O group, host connection, storage system	The number of milliseconds that it took to complete all stage operations in the volume cache. That is, the time that it took to do read operations from the disk to the volume cache.
Cache Stage Service Time - Volume Copy Cache	619	IBM Storage Virtualize¹: volume, pool, node, I/O group, host connection, storage system	The number of milliseconds that it took to complete all stage operations in the volume copy cache. That is, the time that it took to do read operations from the disk to the volume copy cache.
Cache Destage Service Time - Volume Cache	622	IBM Storage Virtualize¹: volume, pool, node, I/O group, host connection, storage system	The number of milliseconds that it took to complete all destage operations in the volume cache. That is, the time that it took to do write operations from the volume cache to the disk.
Cache Destage Service Time - Volume Copy Cache	621	IBM Storage Virtualize¹: volume, pool, node, I/O group, host connection, storage system	The number of milliseconds that it took to complete all destage operations in the volume copy cache. That is, the time that it took to do write operations from the volume copy cache to the disk.
Cache Data Transfer Service Time	179	IBM Storage Virtualize¹: volume, pool, node, I/O group, host connection, storage system	The number of milliseconds that is taken to transfer a track from the cache to the host, including any queuing time that occurs because of throttling. This is similar to the Host Attributed Service Time but includes any queuing delay incurred at the host layer.
Exclusive Track Lock Latency - Volume Cache	638	IBM Storage Virtualize¹: volume, pool, node, I/O group, host connection, storage system	The average number of microseconds that it took to acquire an exclusive track lock at the volume cache.
Exclusive Track Lock Latency - Volume Copy Cache	637	IBM Storage Virtualize¹: volume, pool, node, I/O group, host connection, storage system	The average number of microseconds that it took to acquire an exclusive track lock at the volume copy cache.
Shared Track Lock Latency - Volume Cache	640	IBM Storage Virtualize¹: volume, pool, node, I/O group, host connection, storage system	The average number of microseconds that it took to acquire a shared track lock at the volume cache.
Shared Track Lock Latency - Volume Copy Cache	639	IBM Storage Virtualize¹: volume, pool, node, I/O group, host connection, storage system	The average number of microseconds that it took to acquire a shared track lock at the volume copy cache.
Cache Queue Time IOCB - Volume Cache	642	IBM Storage Virtualize¹: node	The average number of microseconds that the volume cache spent queuing for I/O control blocks.
Cache Queue Time IOCB - Volume Copy Cache	641	IBM Storage Virtualize¹: node	The average number of microseconds that the volume copy cache spent queuing for I/O control blocks.
Cache Queue Time CTCB - Volume Cache	644	IBM Storage Virtualize¹: node	The average number of microseconds that the volume cache spent queuing for cache track control blocks.
Cache Queue Time CTCB - Volume Copy Cache	643	IBM Storage Virtualize¹: node	The average number of microseconds that the volume copy cache spent queuing for cache track control blocks.
Cache Queue Time PNRC - Volume Cache	646	IBM Storage Virtualize¹: node	The average number of microseconds that the volume cache spent queuing for remote credits on a preferred node.
Cache Queue Time PNRC - Volume Copy Cache	645	IBM Storage Virtualize¹: node	The average number of microseconds that the volume copy cache spent queuing for remote credits on a preferred node.
Cache Queue Time NNRC - Volume Cache	648	IBM Storage Virtualize¹: node	The average number of microseconds that the volume cache spent queuing for remote credits on a non-preferred node.
Cache Queue Time NNRC - Volume Copy Cache	647	IBM Storage Virtualize¹: node	The average number of microseconds that the volume copy cache spent queuing for remote credits on a non-preferred node.
Cache Queue Time ARC - Volume Cache	650	IBM Storage Virtualize¹: node	The average number of microseconds that the volume cache spent queuing for remote credits for administrative tasks.
Cache Queue Time ARC - Volume Copy Cache	649	IBM Storage Virtualize¹: node	The average number of microseconds that the volume copy cache spent queuing for remote credits for administrative tasks.
Cache Queue Time CDCB - Volume Cache	652	IBM Storage Virtualize¹: node	The average number of microseconds that the volume cache spent queuing for control blocks in the cache directory.
Cache Queue Time CDCB - Volume Copy Cache	651	IBM Storage Virtualize¹: node	The average number of microseconds that the volume copy cache spent queuing for control blocks in the cache directory.
Cache Queue Time CBR - Volume Cache	654	IBM Storage Virtualize¹: node	The average number of microseconds that the volume cache spent queuing for buffer resources.
Cache Queue Time CBR - Volume Copy Cache	653	IBM Storage Virtualize¹: node	The average number of microseconds that the volume copy cache spent queuing for buffer resources.
Cache Queue Time CHR - Volume Cache	656	IBM Storage Virtualize¹: node	The average number of microseconds that the volume cache spent queuing for hardening rights.
Cache Queue Time CHR - Volume Copy Cache	655	IBM Storage Virtualize¹: node	The average number of microseconds that the volume copy cache spent queuing for hardening rights.
Note: This counter is only available for resources that are running IBM Storage Virtualize 7.3 or later.

Table 5. Volume cache counters
Counter	Counter type	Resource or component type	Description
Disk to Cache Transfer Count (normal)	031	DS8000: volume, array, controller, storage system	Number of tracks transferred from disk to cache, for nonsequential I/O requests, for a particular component over a particular time interval.
Disk to Cache Transfer Count (sequential)	032	DS8000: volume, array, controller, storage system	Number of tracks transferred from disk to cache, for sequential I/O requests, for a particular component over a particular time interval.
Cache to Disk Transfer Count	033	DS8000: volume, array, controller, storage system	Number of tracks transferred from cache to disk, for both sequential and nonsequential I/O requests, for a particular component over a particular time interval.
Prestage Track Count	078	IBM Storage Virtualize: volume, node, I/O group, storage system	Number of prestage reads (tracks of read-ahead data) initiated for a particular component over a particular time interval
Destage Track Count	079	IBM Storage Virtualize: volume, node, I/O group, storage system	Number of destage writes (tracks of dirty write data) initiated for a particular component over a particular time interval.
Prestage Tracks Cache Hits	080	IBM Storage Virtualize: volume, node, I/O group, storage system	Number of read track cache hits that were serviced from prestaged tracks for a particular component over a particular time interval. Included as part of the “Read Track Cache Hits”.
Destage Tracks Cache Hits	081	IBM Storage Virtualize: volume, node, I/O group, storage system	The number of write track cache hits for a particular component over a particular time interval. That is, the track writes that modified only data that was already marked “dirty” in the cache.
Prestage Sector Count	082	IBM Storage Virtualize: node	Number of prestage sectors (sectors of read-ahead data) initiated for a particular component over a particular time interval
Destage Sector Count	083	IBM Storage Virtualize: node	Number of destage writes (sectors of dirty write data) initiated for a particular component over a particular time interval.
Prestage Tracks Cache Hits Sector Count	084	IBM Storage Virtualize: node	Number of sectors read for cache hits that were serviced from prestaged tracks for a particular component over a particular time interval. Included as part of the “Read Track Cache Hits Sector Count”.
Destage Tracks Cache Hits Sector Count	085	IBM Storage Virtualize: node	The number of sectors written for cache hits for a particular component over a particular time interval. That is, the writes that modified only data that was already marked “dirty” in the cache.
Read Sector Count - Volume Cache	62	IBM Storage Virtualize: volume, pool, node, I/O group, host connection, storage system	The number of cache sectors or tracks read by the volume cache. For resources that are running a version of IBM Storage Virtualize that is earlier than 7.3, the unit of the counter is tracks.
Read Sector Count - Volume Copy Cache	601	IBM Storage Virtualize¹: volume, pool, node, I/O group, host connection, storage system	The number of cache sectors read by the volume copy cache.
Write Sector Count - Volume Cache	63	IBM Storage Virtualize: volume, pool, node, I/O group, host connection, storage system	The number of cache sectors or tracks written by the volume cache. For resources that are running a version of IBM Storage Virtualize that is earlier than 7.3, the unit of the counter is tracks.
Write Sector Count - Volume Copy Cache	602	IBM Storage Virtualize¹: volume, pool, node, I/O group, host connection, storage system	The number of cache sectors written by the volume copy cache.
Fast Write Mode Count - Volume Cache	65	IBM Storage Virtualize: volume, pool, node, I/O group, host connection, storage system	The number of cache sectors or tracks written in fast-write mode in the volume cache. For resources that are running a version of IBM Storage Virtualize that is earlier than 7.3, the unit of the counter is tracks.
Fast Write Mode Count - Volume Copy Cache	603	IBM Storage Virtualize¹: volume, pool, node, I/O group, host connection, storage system	The number of cache sectors written in fast-write mode in the volume copy cache.
Flush-through Mode Count - Volume Cache	67	IBM Storage Virtualize¹: volume, pool, node, I/O group, host connection, storage system	The number of cache sectors or tracks written in flush-through write mode in the volume cache. For resources that are running a version of IBM Storage Virtualize that is earlier than 7.3, the unit of the counter is tracks.
Flush-through Mode Count - Volume Copy Cache	604	IBM Storage Virtualize¹: volume, pool, node, I/O group, host connection, storage system	The number of cache sectors written in flush-through write mode in the volume copy cache.
Write-through Mode Count - Volume Cache	66	IBM Storage Virtualize¹: volume, pool, node, I/O group, host connection, storage system	The number of cache sectors or tracks written in write-through write mode in the volume cache. For resources that are running a version of IBM Storage Virtualize that is earlier than 7.3, the unit of the counter is tracks.
Write-through Mode Count - Volume Copy Cache	605	IBM Storage Virtualize¹: volume, pool, node, I/O group, host connection, storage system	The number of cache sectors written in write-through write mode in the volume copy cache.
Cache Overflow Mode Track Count	068	IBM Storage Virtualize¹: volume, pool, node, I/O group, host connection, storage system	The number of cache track that were processed in Cache-Overflow write mode.
Prestage Count	78	IBM Storage Virtualize: volume, pool, node, I/O group, host connection, storage system	The number of cache sectors or tracks prestaged into the volume copy cache. For resources that are running a version of IBM Storage Virtualize that is earlier than 7.3, the unit of the counter is tracks.
Destage Count - Volume Cache	79	IBM Storage Virtualize¹: volume, pool, node, I/O group, host connection, storage system	The number of cache sectors or tracks destaged from the volume cache. For resources that are running a version of IBM Storage Virtualize that is earlier than 7.3, the unit of the counter is tracks.
Destage Count - Volume Copy Cache	606	IBM Storage Virtualize¹: volume, pool, node, I/O group, host connection, storage system	The number of cache sectors destaged from the volume copy cache.
Cache Data Transfer Count	178	IBM Storage Virtualize¹: volume, pool, node, I/O group, host connection, storage system	The number of tracks transferred from the volume cache to the host I/O layer. In combination with the Cache Data Transfer Service Time counter determines the Data Transfer Response Time.
Note: This counter is only available for resource that are running IBM Storage Virtualize 7.3 or later.

Table 6. Volume miscellaneous counters
Counter	Counter type	Resource or component type	Description
NVS Allocation Count	034	DS8000: volume	Number of NVS space allocations for a particular component over a particular time interval.
DFW I/O Count (normal)	035	DS8000: volume, array, controller, storage system	Number of nonsequential “DASD Fast Write” requests for a particular component over a particular time interval. This value typically applies only for count-key data (CKD).
DFW I/O Count (sequential)	036	DS8000: volume, array, controller, storage system	Number of sequential “DASD Fast Write” requests for a particular component over a particular time interval. This value typically applies only for CKD.
DFW Delayed I/O Count	037	DS8000: volume, array, controller, storage system	Number of I/O requests that were delayed due to nonvolatile storage (NVS) space constraints, for a particular component over a particular time interval.
Cache Delayed I/O Count	038	DS8000: volume	Number of I/O requests that were delayed due to cache space constraints, for a particular component over a particular time interval.
Record Mode Read I/O Count	039	DS8000: volume, array, controller, storage system	Number of record-mode read I/O operations for a particular component over a particular time interval.
Record Mode Read Cache Hits	040	DS8000: volume, array, controller, storage system	Number of cache hits for record-mode read I/O operations for a particular component over a particular time interval.
Quick Write Promote Count	041	DS8000: volume, array, controller, storage system	Number of quick write promote operations for a particular component over a particular time interval. This value typically applies only for CKD.
CFW Read I/O Count	042	DS8000: volume	Number of “Cache Fast Write” read I/O requests for a particular component over a particular time interval. This value typically applies only for CKD.
CFW Write I/O Count	043	DS8000: volume	Number of “Cache Fast Write” write I/O requests for a particular component over a particular time interval. This value typically applies only for CKD.
CFW Read Hits	044	DS8000: volume	Number of cache hits for “Cache Fast Write” read I/O requests for a particular component over a particular time interval. This value typically applies only for CKD.
CFW Write Hits	045	DS8000: volume	Number of cache hits for “Cache Fast Write” write I/O requests for a particular component over a particular time interval. This value typically applies only for CKD.
XRC Read Count	046	DS8000: volume	Number of track reads from the Concurrent Copy or XRC Sidefile for a particular component over a particular time interval. This value typically applies only for CKD.
XRC Contaminating Write Count	047	DS8000: volume	Number of contaminating writes for Concurrent Copy or XRC operations for a particular component over a particular time interval. This value typically applies only for CKD.
PPRC Transfer Count	048	DS8000: volume, array, controller, storage system	Number of tracks or portions of tracks that were transferred to the secondary device of a Peer-to-Peer Remote Copy (PPRC) pair, for a particular component over a particular time interval. This counter shows the activity for the source of the PPRC relationship, but shows no activity for the target.
ITA I/O Count	049	DS8000: volume	Number of irregular track access I/O requests, for a particular component over a particular time interval. This value typically applies only for CKD.
ITA Hits	050	DS8000: volume	Number of cache hits for irregular track access I/O requests, for a particular component over a particular time interval. This value typically applies only for CKD.
Rank Read I/O Count	051	DS8000: volume	Number of read I/O operations issued to the physical arrays associated with a particular component over a particular time interval.
Rank Write I/O Count	052	DS8000: volume	Number of write I/O operations issued to the physical arrays associated with a particular component over a particular time interval.
Rank Read Data Chunk Count	053	DS8000: volume	Number of 128 KB chunks (128*2^10 bytes) of data transferred for read I/O operations issued to the physical arrays associated with a particular component over a particular time interval.
Rank Write Data Chunk Count	054	DS8000: volume	Number of 128 KB chunks (128*2^10 bytes) of data transferred for write I/O operations issued to the physical arrays associated with a particular component over a particular time interval.
Rank Read Service Periods	055	DS8000: volume	Number of 16 millisecond time periods that it took to service all read operations issued to the physical arrays associated with a particular component over a particular time interval.
Rank Write Service Periods	056	DS8000: volume	Number of 16 millisecond time periods that it took to service all write operations issued to the physical arrays associated with a particular component over a particular time interval.
ICL Read I/O Count	057	DS8000: volume	Number of Inhibit Cache Loading I/O requests, for a particular component over a particular time interval. This value typically applies only for CKD.
BC Write I/O Count	058	DS8000: volume	Number of Bypass Cache I/O requests, for a particular component over a particular time interval. This value typically applies only for CKD.
Rank Transfer Time	059	DS8000: volume	Number of milliseconds of lower-interface I/O activity, for a particular component over a particular time interval. This value typically applies only for CKD.
Read Cache KB Count	086	IBM Storage Virtualize: volume, node, I/O group, storage system	Amount of read cache, in KB, that was in use for a particular component, at the start of the particular time interval.
Write Cache KB Count	087	IBM Storage Virtualize: volume, node, I/O group, storage system	Amount of write cache, in KB, that was in use for a particular component, at the start of the particular time interval.

Table 7. Volume special computed values
Counter	Counter type	Resource or component type	Description
Cache Holding Time	060	DS8000: controller, storage system	Average cache holding time, in seconds, for I/O data in this subsystem controller (cluster). Shorter time periods indicate adverse performance.
Utilization Percentage	061	DS8000: volume, array, controller, storage system IBM Storage Virtualize: volume, node, I/O group, storage system XIV: volume	Approximate utilization percentage for a particular component over a particular time interval. The value is multiplied by 100 to gain 2 extra digits of precision; for example, 3860 would indicate that the component is running at approximately 38.6% of capacity. The value might exceed 100% to indicate stress beyond the capacity of the component.
Compression CPU Utilization	175	IBM Storage Virtualize: node, I/O group, storage system	The approximate percentage of time that the processors used for data compression I/O tasks are busy.
System CPU Core Utilization	176 (Core 1 to 8) 185 (Core 9 to 16) 186 (Core 17 to 24) 187 (Core 25 to 32)	IBM Storage Virtualize: node, I/O group, storage system	The approximate percentage of time that each set of eight processor cores was busy with system I/O tasks. The value is encoded such that each byte contains the percentage of one of the cores; the low-order byte is for core 1.
Compression CPU Core Utilization	177 (Core 1 to 8) 188 (Core 9 to 16) 189 (Core 17 to 24) 190 (Core 25 to 32)	IBM Storage Virtualize: node, I/O group, storage system	The approximate percentage of time that each set of eight processor cores was busy with data compression tasks. The value is encoded such that each byte contains the percentage of one of the cores; the low-order byte is for core 1.

Disk counters

Performance counters for back-end storage systems are divided into the following categories:

Back-end storage system I/O counters
Back-end storage system data counters
Back-end storage system service time counters
Other back-end counters for storage systems

Table 8. Back-end storage system I/O counters
Counter	Counter type	Resource or component type	Description
Backend Read I/O Count	201	DS8000: rank, array, controller, storage system IBM Storage Virtualize: managed disk, pool, node, I/O group, storage system	Number of I/O operations for read requests, for a particular component over a particular time interval.
Backend Write I/O Count	202	DS8000: rank, array, controller, storage system IBM Storage Virtualize: managed disk, pool, node, I/O group, storage system	Number of I/O operations for write requests, for a particular component over a particular time interval.

Table 9. Back-end storage systems data counters
Counter	Counter type	Resource or component type	Description
Backend Read KB Count	204	IBM Storage Virtualize: managed disk, pool, node, I/O group, storage system IBM FlashSystem 900: flash module, storage system	Number of KB (2^10 bytes) of data that were transferred for read operations, for a particular component over a particular time interval.
Backend Write KB Count	205	IBM Storage Virtualize: managed disk, pool, node, I/O group, storage system IBM FlashSystem 900: flash module, storage system	Number of KB (2^10 bytes) of data that were transferred for write operations, for a particular component over a particular time interval.
Backend Read Data Count	207	DS8000: rank, array, controller, storage system	Number of 128 KB chunks (128*2^10 bytes) of data that were transferred for read operations, for a particular component over a particular time interval.
Backend Write Data Count	208	DS8000: rank, array, controller, storage system	Number of 128 KB chunks (128*2^10 bytes) of data that were transferred for write operations, for a particular component over a particular time interval.

Table 10. Back-end service time counters
Counter	Counter type	Resource or component type	Description
Backend Read Service Time	210	IBM Storage Virtualize: managed disk, pool, node, I/O group, storage system	Number of milliseconds that it took to service all read operations, for a particular component over a particular time interval. For IBM Storage Virtualize, this value is the external response time of the managed disk.
Backend Write Service Time	211	IBM Storage Virtualize: managed disk, pool, node, I/O group, storage system	Number of milliseconds that it took to service all write operations, for a particular component over a particular time interval. For IBM Storage Virtualize, this value is the external response time of the managed disk.
Backend Read Service Periods	213	DS8000: rank, array, controller, storage system	Number of 16 millisecond time periods that it took to service all read operations, for a particular component over a particular time interval.
Backend Write Service Periods	214	DS8000: rank, array, controller, storage system	Number of 16 millisecond time periods that it took to service all write operations, for a particular component over a particular time interval.
Backend Read Queued Service Time	216	IBM Storage Virtualize: managed disk, pool, node, I/O group, storage system	Number of milliseconds that it took to service all read operations, for a particular component over a particular time interval. Includes the time that pending I/O operations spent on the queue waiting to be issued to the backend disk device.
Backend Write Queued Service Time	217	IBM Storage Virtualize: managed disk, pool, node, I/O group, storage system	Number of milliseconds that it took to service all write operations, for a particular component over a particular time interval. Includes the time that pending I/O operations spent on the queue waiting to be issued to the backend disk device.
Peak Backend Read Response Time	219	IBM Storage Virtualize: managed disk, pool, node, I/O group, storage system	The peak (worst) response time for disk reads for a particular component over a particular time interval, in microseconds. For IBM Storage Virtualize, this value is the peak external response time of the managed disks.
Peak Backend Write Response Time	220	IBM Storage Virtualize: managed disk, pool, node, I/O group, storage system	The peak (worst) response time for disk writes for a particular component over a particular time interval, in microseconds. For IBM Storage Virtualize, this is the peak external response time of the managed disks.
Peak Backend Read Queued Response Time	222	IBM Storage Virtualize: managed disk, pool, node, I/O group, storage system	The peak (worst) response time for disk reads for a particular component over a particular time interval, in microseconds. Includes the time that pending I/O operations spent on the queue waiting to be issued to the backend disk device.
Peak Backend Write Queued Response Time	223	IBM Storage Virtualize: managed disk, pool, node, I/O group, storage system	The peak (worst) response time for disk reads for a particular component over a particular time interval, in microseconds. Includes the time that pending I/O operations spent on the queue waiting to be issued to the backend disk device.

Table 11. Other back-end counters for storage systems
Counter	Counter type	Resource or component type	Description
Flash Health Percentage	238	Flash module, storage system	The overall flash module health. The health percentage is calculated based on the number of unusable blocks on the flash module.

Storage system and switch port counters

Performance counters for ports and fabrics are divided into the following categories:

Storage system and switch port I/O or frame counters
Storage system and switch port data counters
Storage system port service time counters
Storage system and switch port utilization percentages
Storage system and switch port error counts

Table 12. Storage system and switch port I/O or frame counters
Counter	Counter type	Resource or component type	Description
Port Send I/O Count	401	DS8000: port, storage system IBM FlashSystem 900: port XIV: port	Number of read I/O operations processed (or write I/O operations initiated) by a particular component over a particular time interval. For ports, available only for hourly/daily data.
Port Receive I/O Count	402	DS8000: port, storage system IBM FlashSystem 900: port XIV: port	Number of write I/O operations processed (or read operations initiated) by a particular component over a particular time interval. For ports, available only for hourly/daily data.
Total Port I/O Count	403	SMI-S BSP: port	Total number of read and write I/O operations processed by a particular component over a particular time interval.
Port Send Frame Count	404	Switch port Outer-switch connection¹ Switch	Number of frames sent by a particular component over a particular time interval.
Port Receive Frame Count	405	Switch port Inter-switch connection¹ Switch	Number of frames received by a particular component over a particular time interval.
Total Port Frame Count	406	Switch port Inter-switch connection¹ Switch	Number of frames sent and received by a particular component over a particular time interval.
Port FB Send I/O Count	407	DS8000: port	Number of read I/O operations processed (or write operations initiated) for FB requests, for a particular port over a particular time interval.
Port FB Receive I/O Count	408	DS8000: port	Number of write I/O operations processed (or read operations initiated) for FB requests, for a particular port over a particular time interval.
Port CKD Send I/O Count	410	DS8000: port	Number of read I/O operations processed (or write operations initiated) for CKD requests, for a particular port over a particular time interval.
Port CKD Receive I/O Count	411	DS8000: port	Number of write I/O operations processed (or read operations initiated) for CKD requests, for a particular port over a particular time interval.
Port PPRC Send I/O Count	413	DS8000: port, storage system	Number of write operations initiated by the PPRC primary, for a particular port over a particular time interval.
Port PPRC Receive I/O Count	414	DS8000: port, storage system	Number of write operations processed by the PPRC secondary, for a particular port over a particular time interval.
Port to Host Send I/O Count	442	IBM Storage Virtualize: port, node, I/O group, storage system	Number of exchanges (I/Os) initiated to host computers from a particular port over a particular time interval.
Port to Host Receive I/O Count	443	IBM Storage Virtualize: port, node, I/O group, storage system	Number of exchanges (I/Os) received from host computers by a particular port over a particular time interval.
Port to Disk Send I/O Count	445	IBM Storage Virtualize: port, node, I/O group, storage system	Number of exchanges (I/Os) initiated to storage systems from a particular port over a particular time interval.
Port to Disk Receive I/O Count	446	IBM Storage Virtualize: port, node, I/O group, storage system	Number of exchanges (I/Os) received from storage systems by a particular port over a particular time interval.
Port to Local Send I/O Count	448	IBM Storage Virtualize: port, node, I/O group, storage system	Number of exchanges (I/Os) initiated to other IBM Storage Virtualize nodes on the local IBM Storage Virtualize cluster from a particular port over a particular time interval.
Port to Local Receive I/O Count	449	IBM Storage Virtualize: port, node, I/O group, storage system	Number of exchanges (I/Os) received from other IBM Storage Virtualize nodes on the local cluster by a particular port over a particular time interval.
Port to Remote Send I/O Count	451	IBM Storage Virtualize: port, node, I/O group, storage system	Number of exchanges (I/Os) initiated to a remote IBM Storage Virtualize cluster from a particular port over a particular time interval.
Port to Remote Receive I/O Count	452	IBM Storage Virtualize: port, node, I/O group, storage system	Number of exchanges (I/Os) received from a remote cluster by a particular port over a particular time interval.
Port to Local Send Message Count	478	IBM Storage Virtualize: node, I/O group, storage system	Number of messages sent to nodes on the local IBM Storage Virtualize cluster, by the ports associated with a particular component, over a particular time interval. This count might be larger or smaller than the Port to Local Send I/O Count, because multiple small messages might be batched into a single I/O, or a single large message split between multiple I/Os.
Port to Local Receive Message Count	479	IBM Storage Virtualize: node, I/O group, storage system	Number of messages received from nodes on the local IBM Storage Virtualize cluster, by the ports associated with a particular component, over a particular time interval. This count might be larger or smaller than the Port to Local Receive I/O Count, because multiple small messages might be batched into a single I/O, or a single large message split between multiple I/Os.
Port to Remote Send Message Count	481	IBM Storage Virtualize: node, I/O group, storage system	Number of messages sent to nodes on the remote IBM Storage Virtualize cluster, by the ports associated with a particular component, over a particular time interval. This count might be larger or smaller than the Port to Remote Send I/O Count, because multiple small messages might be batched into a single I/O, or a single large message split between multiple I/Os.
Port to Remote Receive Message Count	482	IBM Storage Virtualize: node, I/O group, storage system	Number of messages received from nodes on the remote IBM Storage Virtualize cluster, by the ports associated with a particular component, over a particular time interval. This count might be larger or smaller than the Port to Remote Receive I/O Count, because multiple small messages might be batched into a single I/O, or a single large message split between multiple I/Os.
Note: Performance data for inter-switch connections contains performance data for the following resources: Switch ports on ISLs and NPV links. Switch trunks for ISL trunks, ICL trunks, F_port channels, and port channels. The performance data for both resources is displayed together in the IBM Spectrum Control GUI. However, to obtain this data from the CLI, you must run separate queries.

Table 13. Storage system and switch port data counters
Counter	Counter type	Resource or component type	Description
Port Send KB Count	416	DS8000: storage system IBM FlashSystem 900: port Switch port Inter-switch connection¹ Switch XIV: port	Number of KB (2^10 bytes) of data that were sent from a particular component over a particular time interval. This value is read KB if the port is the target of a read operation, or write KB if the port is the initiator of a write operation (for example, a PPRC primary).
Port Receive KB Count	417	DS8000: storage system IBM FlashSystem 900: port Switch port Inter-switch connection¹ Switch XIV: port	Number of KB (2^10 bytes) of data that were received by a particular component over a particular time interval. This value is write KB if the port is the target of a write operation, or read KB if the port is the initiator of a read operation.
Total Port KB Count	418	Switch port Inter-switch connection¹ Switch SMI-S BSP: port	Total number of KB (2^10 bytes) of data that were transferred, by a particular port over a particular time interval.
Port Peak Send Data Rate²	419	Switch port Inter-switch connection¹ Switch	Peak number of megabytes (2^20 bytes) per second that were sent by a particular port over a time interval.
Port Peak Receive Data Rate	420	Switch port Inter-switch connection¹ Switch	Peak number of megabytes (2^20 bytes) per second that were received by a particular port over a time interval.
Port FB Send Data Count	421	DS8000: port	Number of 128 KB chunks (128*2^10 bytes) of data that were sent for FB requests, from a particular component over a particular time interval. This value is read KB if the port is the target of a read operation, or write KB if the port is the initiator of a write operation (for example, a PPRC primary).
Port FB Receive Data Count	422	DS8000: port	Number of 128 KB chunks (128*2^10 bytes) of data that were received for FB requests, by a particular component over a particular time interval. This value is write KB if the port is the target of a write operation, or read KB if the port is the initiator of a read operation.
Port CKD Send Data Count	424	DS8000: port	Number of 128 KB chunks (128*2^10 bytes) of data that were sent for CKD requests, from a particular component over a particular time interval. This value is read KB if the port is the target of a read operation, or write KB if the port is the initiator of a write operation (for example, a PPRC primary).
Port CKD Receive Data Count	425	DS8000: port	Number of 128 KB chunks (128*2^10 bytes) of data that were received for CKD requests, by a particular component over a particular time interval. This value is write KB if the port is the target of a write operation, or read KB if the port is the initiator of a read operation.
Port PPRC Send Data Count	427	DS8000: port, storage system	Number of 128 KB chunks (128*2^10 bytes) of data that were sent by a particular port over a particular time interval, as result of write operations initiated by a PPRC primary.
Port PPRC Receive Data Count	428	DS8000: port, storage system	Number of 128 KB chunks (128*2^10 bytes) of data that were received by a particular port over a particular time interval, as result of write operations processed by a PPRC secondary.
Port to Host Send KB Count	454	IBM Storage Virtualize: port, node, I/O group, storage system	Number of KB of data sent to host computers from a particular port over a particular time interval.
Port to Host Receive KB Count	455	IBM Storage Virtualize: port, node, I/O group, storage system	Number of KB of data received from host computers by a particular port over a particular time interval.
Port to Disk Send KB Count	457	IBM Storage Virtualize: port, node, I/O group, storage system	Number of KB of data sent to storage systems from a particular port over a particular time interval.
Port to Disk Receive KB Count	458	IBM Storage Virtualize: port, node, I/O group, storage system	Number of KB of data received from storage systems by a particular port over a particular time interval.
Port to Local Send KB Count	460	IBM Storage Virtualize: port, node, I/O group, storage system	Number of KB of data sent to other IBM Storage Virtualize nodes on the local IBM Storage Virtualize cluster from a particular port over a particular time interval.
Port to Local Receive KB Count	461	IBM Storage Virtualize: port, node, I/O group, storage system	Number of KB of data received from other IBM Storage Virtualize nodes on the local cluster by a particular port over a particular time interval.
Port to Remote Send KB Count	463	IBM Storage Virtualize: port, node, I/O group, storage system	Number of KB of data sent to a remote IBM Storage Virtualize cluster from a particular port over a particular time interval.
Port to Remote Receive KB Count	464	IBM Storage Virtualize: port, node, I/O group, storage system	Number of KB of data received from a remote IBM Storage Virtualize cluster by a particular port over a particular time interval.
Note: Performance data for inter-switch connections contains performance data for the following resources: Switch ports on ISLs and NPV links. Switch trunks for ISL trunks, ICL trunks, F_port channels, and port channels. The performance data for both resources is displayed together in the IBM Spectrum Control GUI. However, to obtain this data from the CLI, you must run separate queries. This counter is available only for ports on Brocade switches.

Table 14. Storage system port service time counters
Counter	Counter type	Resource or component type	Description
Port Send Service Time	430	DS8000: storage system IBM FlashSystem 900: port XIV: port	Number of milliseconds it took to service all send operations, for a particular component over a particular time interval. This value is read times, if the port is the target of a read operation, or write times if the port is the initiator of a write operation (for example, a PPRC primary).
Port Receive Service Time	431	DS8000: storage system IBM FlashSystem 900: port XIV: port	Number of milliseconds it took to service all receive operations, for a particular port over a particular time interval. This value is write times, if the port is the target of a write operation, or read times if the port is the initiator of a read operation.
Port FB Send Service Periods	433	DS8000: port	Number of 16 millisecond periods it took to service all send operations for FB requests, for a particular component over a particular time interval. This value is read times, if the port is the target of a read operation, or write times if the port is the initiator of a write operation (for example, a PPRC primary).
Port FB Receive Service Periods	434	DS8000: port	Number of 16 millisecond periods it took to service all receive operations for FB requests, for a particular component over a particular time interval. This value is write times, if the port is the target of a write operation, or read times if the port is the initiator of a read operation.
Port CKD Send Service Periods	436	DS8000: port	Number of 16 millisecond periods it took to service all send operations for CKD requests, for a particular component over a particular time interval. This value is read times, if the port is the target of a read operation, or write times if the port is the initiator of a write operation (for example, a PPRC primary).
Port CKD Receive Service Periods	437	DS8000: port	Number of 16 millisecond periods it took to service all receive operations for CKD requests, for a particular component over a particular time interval. This value is write times, if the port is the target of a write operation, or read times if the port is the initiator of a read operation.
Port PPRC Send Service Periods	439	DS8000: port, storage system	Number of 16 millisecond periods it took to service write requests by a PPRC primary, for a particular port over a particular time interval.
Port PPRC Receive Service Periods	440	DS8000: port, storage system	Number of 16 millisecond periods it took to service write requests by a PPRC secondary, for a particular port over a particular time interval.
Port to Local Send Service Time	466	IBM Storage Virtualize: node, I/O group, storage system	Number of milliseconds it took to service all send operations to other nodes on the local IBM Storage Virtualize cluster, for a particular component over a particular time interval. For IBM Storage Virtualize, this value is the external service time of the transfers.
Port to Local Receive Service Time	467	IBM Storage Virtualize: node, I/O group, storage system	Number of milliseconds it took to service all receive operations from other nodes on the local IBM Storage Virtualize cluster, for a particular component over a particular time interval. For IBM Storage Virtualize, this value is the external service time of the transfers.
Port to Local Send Queued Service Time	469	IBM Storage Virtualize: node, I/O group, storage system	Number of milliseconds it took to service all send operations to other nodes on the local IBM Storage Virtualize cluster, including the time that pending operations spent on the queue, for a particular component over a particular time interval. For IBM Storage Virtualize, this value is the queued service time of the transfers.
Port to Local Receive Queued Service Time	470	IBM Storage Virtualize: node, I/O group, storage system	Number of milliseconds it took to service all receive operations from other nodes on the local IBM Storage Virtualize cluster, including the time that pending operations spent on the queue, for a particular component over a particular time interval. For IBM Storage Virtualize, this value is the queued service time of the transfers.
Port to Remote Send Service Time	472	IBM Storage Virtualize: node, I/O group, storage system	Number of milliseconds it took to service all send operations to nodes on the remote IBM Storage Virtualize cluster, for a particular component over a particular time interval. For IBM Storage Virtualize, this value is the external service time of the transfers.
Port to Remote Receive Service Time	473	IBM Storage Virtualize: node, I/O group, storage system	Number of milliseconds it took to service all receive operations from nodes on the remote IBM Storage Virtualize cluster, for a particular component over a particular time interval. For IBM Storage Virtualize, this value is the queued service time of the transfers.
Port to Remote Send Queued Service Time	475	IBM Storage Virtualize: node, I/O group, storage system	Number of milliseconds it took to service all send operations to nodes on the remote IBM Storage Virtualize cluster, including the time that pending operations spent on the queue, for a particular component over a particular time interval. For IBM Storage Virtualize, this value is the queued service time of the transfers.
Port to Remote Receive Queued Service Time	476	IBM Storage Virtualize: node, I/O group, storage system	Number of milliseconds it took to service all receive operations from nodes on the remote IBM Storage Virtualize cluster, including the time that pending operations spent on the queue, for a particular component over a particular time interval. For IBM Storage Virtualize, this value is the queued service time of the transfers.

Table 15. Storage system and switch port utilization percentages
Counter	Counter type	Resource or component type	Description
Port Send Utilization Percentage	484	DS8000: port	Approximate percentage of time that the associated port was busy with sending data. The value is multiplied by 100 to give 2 extra digits of precision, for example, 3860 would indicate that the port is busy 38.6% of the time. The port is busy sending data when servicing read I/Os from hosts, and when initiating write I/Os from a PPRC primary.
Port Receive Utilization Percentage	485	DS8000: port	Approximate percentage of time that the associated port was busy with receiving data. The value is multiplied by 100 to give 2 extra digits of precision, for example, 3860 would indicate that the port is busy 38.6% of the time. The port is busy receiving data when servicing non-PPRC write I/Os from hosts, and when servicing write I/Os at a PPRC secondary.
Port Send Bandwidth Percentage	487	DS8000: port IBM FlashSystem 900: port IBM Storage Virtualize: port Switch port Inter-switch connection¹	Approximate percentage of bandwidth utilization for send operations by this port, based on the current negotiated speed of the port. The value is multiplied by 100 to give 2 extra digits of precision, for example, 3860 would indicate that 38.6% of the port bandwidth was being used. The port is busy sending data when servicing read I/Os from hosts, and when initiating write I/Os from a PPRC primary.
Port Receive Bandwidth Percentage	488	DS8000: port IBM FlashSystem 900: port IBM Storage Virtualize: port Switch port Inter-switch connection¹	Approximate percentage of bandwidth utilization for receive operations by this port, based on the current negotiated speed of the port. The value is multiplied by 100 to give 2 extra digits of precision, for example, 3860 would indicate that 38.6% of the port bandwidth was being used. The port is busy receiving data when servicing non-PPRC write I/Os from hosts, and when servicing write I/Os at a PPRC secondary.
Port Link Quality Percentage	490	Switch port Inter-switch connection¹	The estimated link quality of the switch port. The percentage is based on whether the port is an expansion port (E_port) or a fabric port (F_port), and on the error statistics for the port.
Note: Performance data for inter-switch connections contains performance data for the following resources: Switch ports on ISLs and NPV links. Switch trunks for ISL trunks, ICL trunks, F_port channels, and port channels. The performance data for both resources is displayed together in the IBM Spectrum Control GUI. However, to obtain this data from the CLI, you must run separate queries.

Table 16. Storage system and switch port error counts
Counter	Counter type	Resource or component type	Description
Operational Status	501	Switch port Inter-switch connection¹	The operational status of a port over a time interval.
LIP Count	502	Switch port Inter-switch connection¹ Switch	Number of LIP events that occurred on the associated arbitrated loops, for a particular component over a particular time interval.
NOS Count	503	Switch port Inter-switch connection¹ Switch	Number of NOS events that occurred on the associated switched fabrics, for a particular component over a particular time interval.
Error Frame Count²	504	DS8000: port, storage system	Number of frames received in error by a particular component over a particular time interval.
Discarded Frame Count	505	Switch port Inter-switch connection¹ Switch	Number of frames that were lost due to a lack of available host buffers, for a particular component over a particular time interval.
Link Failure Count	506	DS8000®: port, storage system IBM Storage Virtualize: port, node, I/O group, storage system	The number of link errors that were experienced by a particular component over a particular time interval.
Loss of Sync Count	507	DS8000: port, storage system IBM Storage Virtualize: port, node, I/O group, storage system	Number of times that synchronization was lost after the last reset of the device, for a particular component over a particular time interval. Synchronization is assumed lost after a timeout interval identified by the Receiver-Transmitter-Timeout property. This count is part of the Link Error Status Block (LESB).
Loss of Signal Count	508	DS8000: port, storage system IBM Storage Virtualize: port, node, I/O group, storage system	Number of times that the signal was lost after the last reset of the device, for a particular component over a particular time interval. This count is part of the Link Error Status Block (LESB).
CRC Error Count	509	DS8000: port, storage system IBM Storage Virtualize: port, node, I/O group, storage system	Number of frames received in which the CRC in a frame does not match the CRC computed by the receiver. This count is part of the Link Error Status Block (LESB).
Primitive Sequence Protocol Error Count	510	DS8000: port, storage system IBM Storage Virtualize: port, node, I/O group, storage system	Count of primitive sequence protocol errors detected at this port. This count is part of the Link Error Status Block (LESB).
Invalid Transmission Word Count	511	DS8000: port, storage system IBM Storage Virtualize: port, node, I/O group, storage system	Number of transmission words that had an 8b10b code violation in one or more of its characters; had a K28.5 in its second, third, or fourth character positions; or was an ordered set that had an incorrect Beginning Running Disparity. This count is part of the Link Error Status Block (LESB).
Short Frame Count³	512	Switch port Inter-switch connection¹ Switch	Number of frames received that were shorter than 28 octets. The value of 28 is calculated based on an assumption of 24 header bytes plus 4 CRC bytes. The count does not include SOF/EOF bytes which are not data.
Long Frame Count	513	Switch port Inter-switch connection¹ Switch	Number of frames received that were longer than 2140 octets. The value of 2140 is calculated based on an assumption of 24 header bytes plus 4 CRC bytes plus 2112 bytes of payload.
Address Error Count	514	Switch port Inter-switch connection¹ Switch	Count of frames received with unknown addressing. An example is an unknown SID.
Buffer Credit Not Provided Count	515	Switch port Inter-switch connection¹ Switch	Count of occurrences when all input buffers of a port were full and outbound buffer-to-buffer credit transitioned to zero. There is no credit to provide to other side.
Buffer Credit Not Received Count	516	Switch port Inter-switch connection¹ Switch	Count of transitions in/out of Bbcredit zero state. The other side is not providing any credit.
Delimiter Error Count	517	Switch port Inter-switch connection¹ Switch	Count of invalid frame delimiters received at this port. An example is a frame with a class 2 start and a class 3 at the end.
Encoding Disparity Error Count	518	Switch port Inter-switch connection¹ Switch	Count of disparity errors received at this port.
Link Reset Transmitted Count	519	DS8000: port, storage system	Count of link resets. This value is the number of LRs transmitted.
Link Reset Received Count	520	DS8000: port, storage system	Count of link resets. This value is the number LRs received.
Discarded Class 3 Frame Count²	521	Switch port Inter-switch connection¹ Switch	Class3FramesDiscarded is the count of class 3 frames that were discarded upon reception.
Invalid Ordered Set Count	522	Switch port Inter-switch connection¹ Switch	The total number of invalid ordered sets received.
F-BSY Frame Count³	523	Switch port Inter-switch connection¹ Switch	Number of F_BSY frames generated.
P-BSY Frame Count	524	Switch port Inter-switch connection¹ Switch	Number of P_BSY frames generated.
F-RJT Frame Count³	525	Switch port Inter-switch connection¹ Switch	Number of F_BSY frames generated.
P-RJT Frame Count	526	Switch port Inter-switch connection¹ Switch	Number of P_BSY frames generated.
Buffer Credit Zero Error Count	527	Switch port Inter-switch connection¹ Switch	Number of times that frame transmission was blocked by a transmit credit of zero.
Zero Buffer Credit Timer	528	IBM Storage Virtualize: port, node, I/O group, storage system	Number of microseconds for which the port has been unable to send frames due to lack of buffer credit since the last node reset.
Out of Order Data Count	529	DS8000: port, storage system	Number of times that an out of order frame is detected.
Out of Order ACK Count	530	DS8000: port, storage system	Number of times that an out of order ACK frame is detected.
Duplicate Frame Count	531	DS8000: port, storage system	Number of times a frame was received that has been detected as previously processed.
Invalid Relative Offset Count	532	DS8000: port, storage system	Number of times that a frame was received with bad relative offset in the frame header.
Sequence Timeout Count	533	DS8000: port, storage system	Number of times the port has detected a timeout condition on receiving sequence initiative for a fibre channel exchange.
Class 3 Send Timeout Frame Count²	534	Brocade switch port Brocade Inter-switch connection¹ Brocade switch	Average count of class 3 frames per second that were discarded before transmission because of a timeout condition. The timeout condition occurs while the switch or port waits for buffer credit from the receiving port at the other end of the fibre. When you troubleshoot a SAN, use this count to view port conditions that might slow the performance of the resources to which those ports are connected.
Class 3 Receive Timeout Frame Count²	535	Brocade switch port Brocade Inter-switch connection¹ Brocade switch	Average count of class 3 frames per second that were discarded after reception because of a timeout condition. The timeout condition occurs while the transmitting port waits for buffer credit from a port at the other end of the fibre. When you troubleshoot a SAN, use this count to view port conditions that might slow the performance of the resources to which those ports are connected.
RDY Priority Override Count² ³	536	Brocade switch port Brocade Inter-switch connection¹ Brocade switch	Average count of times per second during which the sending of R_RDY or VC_RDY signals was a higher priority than the sending of frames. This condition occurs because of diminishing credit reserves in the transmitter at the other end of the fibre. When you troubleshoot a SAN, use this count to view port conditions that might slow the performance of the resources to which those ports are connected.
Port State Change Rate	537	Brocade switch port Brocade Inter-switch connection¹ Brocade switch	Average count of times per second that the state of a port changes to offline, online, or faulty. When you troubleshoot a SAN, use this count to view port conditions that might slow the performance of the resources to which those ports are connected.
Bad EOF CRC Error Count²	538	Fabrics	The number of cyclic redundancy check (CRC) errors that were detected in frames with a bad end-of-frame (EOF) indicator. In Brocade fabrics, a bad EOF in a frame can indicate that the frame has a known, previously detected CRC error. A good EOF in a frame with a CRC error indicates that the CRC error was not previously detected.
Port Abort Count	539	DS8000: port	The number of times that the port on DS8000 received an abort error.
Extreme I/O Concurrency Count	540	DS8000: port	The number of times that the port on DS8000 had more than 1500 concurrent I/O operations or exchanges. The number of concurrent I/O operations for a port on DS8000 cannot exceed 2000.
I/O Busy Count	541	DS8000: port	The number of times that the port on DS8000 returned a `SCSI Queue Full` or a `Busy` status to the server. Ports can return these statuses if the number of concurrent I/O operations or exchanges exceeds an internal DS8000 threshold.
I/O Overrun Count	542	DS8000: port	The number of times that the port on DS8000 had to discard commands because the number of concurrent I/O operations or exchanges for the port exceeded 2000.
Zero Send Buffer Credit Time²	543	DS8000: port	The number of one-second intervals during which the port on DS8000 had depleted its send buffer credits. That is, the approximate amount of time that the receiving port had no credit to provide to the port on DS8000.
Zero Receive Buffer Credit Time²	544	DS8000: port	The number of one-second intervals during which the port on DS8000 had depleted its receive buffer credits. That is, the approximate amount of time that the port on DS8000 had no credit to provide to the sending port.
Port Transmit Delay Time	547	IBM Storage Virtualize: port	The duration of the delay on the port during send operations, in microseconds. The reason for the delay might be a lack of buffer credits.
Port Transmit Delay Count	548	IBM Storage Virtualize: port	The number of send operations by the port that were delayed. The reason for these delays might be a lack of buffer credits.
Port Transmit Delay Measured Count	549	IBM Storage Virtualize: port	The number of send operations by the port that were measured to allow the detection of any potential transmission delay due to lack of buffer credits.
Note: Performance data for inter-switch connections contains performance data for the following resources: Switch ports on ISLs and NPV links. Switch trunks for ISL trunks, ICL trunks, F_port channels, and port channels. The performance data for both resources is displayed together in the IBM Spectrum Control GUI. However, to obtain this data from the CLI, you must run separate queries. This counter is only available for ports on Brocade switches. You must use an SNMP agent to collect data for this counter.