Performance metrics for XIV, IBM Spectrum Accelerate, IBM® FlashSystem A9000, and IBM FlashSystem A9000R

Monitor the performance metrics that are collected for XIV® systems, IBM Storage Accelerate, IBM FlashSystem A9000, and IBM FlashSystem A9000R.

For XIV systems, IBM FlashSystem A9000, and IBM FlashSystem A9000R, performance metrics are available for the following resources:

Volume metrics
Port metrics

For IBM Storage Accelerate, performance metrics are available for the following resource:

Volume metrics

Restriction: XIV systems, IBM Storage Accelerate, IBM FlashSystem A9000, and IBM FlashSystem A9000R do not track performance statistics for volumes that were never used. Because there are no performance statistics, performance metrics are not shown for these volumes and their related components.

Volume metrics

Volume performance metrics are organized into the following categories:

Key storage metrics
Cache hit percentage metrics
Response time metrics
Miscellaneous metrics

Unless otherwise noted, you can view volume metrics for the following resources:

Volumes
Pools
Modules
Host connections
Storage systems

Table 1. Key volume metrics
Metric	Description
Data Rate (Read)	The average number of MiBs per second that are transferred for read operations.
Data Rate (Write)	The average number of MiBs per second that are transferred for write operations.
Data Rate (Total)	The average number of MiB per second that are transferred for read operations and write operations.
Overall I/O Rate (Read)	The average number of read operations per second. This value includes both sequential and nonsequential read operations.
Overall I/O Rate (Write)	The average number of write operations per second. This value includes both sequential and nonsequential write operations.
Overall I/O Rate (Total)	The average number of read operations and write operations per second. This value includes both sequential and nonsequential operations.
Response Time (Read)	The average number of milliseconds to complete a read operation.
Response Time (Write)	The average number of milliseconds to complete a write operation.
Response Time (Overall)	The average number of milliseconds to complete an I/O operation. This value includes both read and write operations.
Important: For XIV systems, all the key storage metrics are available for 10.2.2 or later.

Table 2. Cache hit percentage metrics
Metric	Description
Data Cache Hits (Read)²	The percentage of all read data that is read from the cache.
Data Cache Hits (Write)²	The percentage of all write data that is written to cache slots that are marked as modified.
Data Cache Hits (Overall)²	The percentage of all data that is handled in the cache. This value includes read data that is read from the cache and write data that is written to cache slots that are marked as modified.
Overall I/O Cache Hits (Read)¹	The percentage of all read operations that find data in the cache. This value includes both sequential and random read operations, and read operations in the volume cache and volume copy cache where applicable. You can use this value to understand throughput or response times. Low cache-hit percentages can increase response times because in the event of a cache miss, the data must be read from the back-end storage resources.
Overall I/O Cache Hits (Write)¹	The average percentage of all write operations that are handled in the cache, across all volumes on the server. This value includes both sequential and nonsequential write operations.
Overall I/O Cache Hits (Total)¹	The percentage of all read operations and write operations that are handled in the cache. This value includes both sequential and random read and write operations, and read and write operations in the volume cache and volume copy cache where applicable. You can use this value to understand throughput or response times. Low cache-hit percentages can increase response times because a cache miss requires access to the back-end storage resources.
SSD Read Cache Hits (I/O)²	The percentage of read operations that find data in the cache on a solid-state drive (SSD). The value for this metric is also included in the value for the Overall Read Cache Hit Percentage metric. This metric is only available for XIV systems that use solid-state drives as drives for caching.
SSD Read Cache Hits (Data)²	The percentage of all read data that was read from cache memory on a solid-state drive. This metric is only available for XIV systems that use solid-state drives as drives for caching.
Notes: For XIV systems, this metric is available in 10.2.2 or later. For XIV systems, this metric is available in 10.2.4 or later.

Table 3. Response time metrics
Metric	Description
Cache Hit Response Time (Read)	The average number of milliseconds to complete a read-cache hit operation.
Cache Hit Response Time (Write)	The average number of milliseconds to complete a write-cache hit operation.
Cache Hit Response Time (Overall)	The average number of milliseconds to complete a cache hit operation. This value includes the times for both read-cache hit and write-cache hit operations.
Cache Miss Response Time (Read)	The average number of milliseconds to complete a read-cache miss operation.
Cache Miss Response Time (Write)	The average number of milliseconds to complete a write-cache miss operation.
Cache Miss Response Time (Overall)	The average number of milliseconds to complete a cache miss operation. This value includes the times for both read-cache miss and write-cache miss operations.
Response Time by Transfer Size (Small)	The average number of milliseconds to complete an I/O operation that has a small data transfer size. A small data transfer has a size that is less than or equal to 8 KiB.
Response Time by Transfer Size (Medium)	The average number of milliseconds to complete an I/O operation that has a medium data transfer size. A medium data transfer has a size that is greater than 8 KiB and less than or equal to 64 KiB.
Response Time by Transfer Size (Large)	The average number of milliseconds to complete an I/O operation that has a large data transfer size. A large data transfer has a size that is greater than 64 KiB and less than or equal to 512 KiB.
Response Time by Transfer Size (Very Large)	The average number of milliseconds to complete an I/O operation with a data transfer size that is greater than 512 KiB.
SSD Read Cache Hit Response Time	The average number of milliseconds that it takes to complete a hit operation on the read cache on a solid-state drive. The value for this metric is also included in the value for the Read Cache Hit Response Time metric.This metric is only available for XIV systems that use solid-state drives as drives for caching.
Note: For XIV systems, all the response time metrics are available for 10.2.2 or later.

Table 4. Miscellaneous metrics
Metric	Description
Average Transfer Size (Read)¹	The average number of KiB that are transferred per read operation.
Average Transfer Size (Write)¹	The average number of KiB that are transferred per write operation.
Average Transfer Size (Overall)¹	The average number of KiB that are transferred per I/O operation. This value includes both read and write operations.
I/O Transfer Size (Small)²	The percentage of I/O operations with a small data transfer size. A small data transfer has a size that is less than or equal to 8 KiB.
I/O Transfer Size (Medium)²	The percentage of I/O operations with a medium data transfer size. A medium data transfer has a size that is greater than 8 KiB and less than or equal to 64 KiB.
I/O Transfer Size (Large)²	The percentage of I/O operations with a large data transfer size. A large data transfer has a size that is greater than 64 KiB and less than or equal to 512 KiB.
I/O Transfer Size (Very Large)²	The percentage of I/O operations with a data transfer size that is greater than 512 KiB.
Data Transfer Size (Small) ²	The percentage of data that is transferred as a result of I/O operations with a small data transfer size. A small data transfer has a size that is less than or equal to 8 KiB.
Data Transfer Size (Medium) ²	The percentage of data that is transferred as a result of I/O operations with a medium data transfer size. A medium data transfer has a size that is greater than 8 KiB and less than or equal to 64 KiB.
Data Transfer Size (Large)²	The percentage of data that is transferred as a result of I/O operations with a large data transfer size. A large data transfer has a size that is greater than 64 KiB and less than or equal to 512 KiB.
Data Transfer Size (Very Large)²	The percentage of data that is transferred as a result of I/O operations with a data transfer size that is greater than 512 KiB.
Volume Utilization^{1, 3}	The average percentage of time that the volume is busy.
Pool Activity Score^{1, 3}	The activity level of pools, which is set to the following value: [Read I/O Rate × (1− Read I/O Cache Hit %)] ÷ Total Pool Capacity The value of this metric is the same for all pools in the storage system.
Notes: For XIV systems, this metric is available in 10.2.2 or later. For XIV systems, this metric is available in 10.2.4 or later. This metric is only available when you view the performance of pools.

Port metrics

The following performance metrics for ports are available for XIV systems that are 10.2.4 or later:

I/O rate metrics
Data rate metrics
Response time metrics
Miscellaneous port metrics

Restriction: Port metrics are not available for IBM Storage Accelerate.

Table 5. I/O rate metrics
Metric	Description
I/O Rate (Send)	The average number of I/O operations per second for operations in which data is sent from a port.
I/O Rate (Receive)	The average number of I/O operations per second for operations in which the port receives data.
I/O Rate (Total)	The average number of send operations and receive operations per second.

Table 6. Data rate metrics
Metric	Description
Data Rate (Send)	The average rate at which data is sent from the port. The rate is measured in MiB per second.
Data Rate (Receive)	The average rate at which data is received by the port. The rate is measured in MiB per second.
Data Rate (Total)	The average rate at which data is transferred through the port. The rate is measured in MiB per second and includes both send and receive operations.

Table 7. Response time metrics
Metric	Description
Response Time (Send)	The average number of milliseconds to complete a send operation.
Response Time (Receive)	The average number of milliseconds to complete a receive operation.
Response Time (Overall)	The average number of milliseconds to complete a send or receive operation.

Table 8. Miscellaneous port metrics
Metric	Description
Bandwidth (Send)	The percentage of the port bandwidth that is used for send operations. This value is an indicator of port bandwidth usage that is based on the speed of the port.
Bandwidth (Receive)	The percentage of the port bandwidth that is used for receive operations. This value is an indicator of port bandwidth usage that is based on the speed of the port.
Bandwidth (Overall)	The percentage of the port bandwidth that is used for send and receive operations. This value is an indicator of port bandwidth usage that is based on the speed of the port.