Performance of One IO Group report

Shows four charts, and a table of performance metrics for an I/O group over a time period. Use the report to analyze the performance of an I/O group.

Restriction: This report applies only to SAN Volume Controller and Storwize® systems.

Charts

The charts show the following performance metrics for an I/O group on a storage system:
  • The total overall I/O rates, and the total response times
  • The overall I/O rates for read and write operations, and the response times for read and write operations
  • The data rates for read and write operations, and the total data rates
  • The overall cache hit percentage for read operations, the cache delay percentage for write operations, and the utilization percentage for processors

Report output

The following information is provided in the report for the period that you specified:
Storage System Name
A user-defined name of the storage system. If a name was not defined, IBM Spectrum® Control shows the name that was defined when the storage system was added for monitoring.
Storage System Configuration
Shows whether a storage system is configured as back-end storage or configured to virtualize back-end storage. If this value is Storage System, the storage system is configured as back-end storage. If this value is Storage Virtualizer, the storage system is configured to virtualize back-end storage.
Storage I/O Group Name
The name that was assigned to the I/O group when it was added to the system.
Overall Read I/O Rate (ops/s)
The average number of read operations per second. This value includes both sequential and nonsequential read operations.
Overall Write I/O Rate (ops/s)
The average number of write operations per second. This value includes both sequential and nonsequential write operations.
Total Overall I/O Rate (ops/s)
The average number of read operations and write operations per second. This value includes both sequential and nonsequential operations.
Read Response Time (ms/op)
The average number of milliseconds to complete a read operation.
Write Response Time (ms/op)
The average number of milliseconds to complete a write operation.
Overall Response Time (ms/op)
The average number of milliseconds to complete an I/O operation. This value includes both read and write operations.
Read Data Rate (MiB/s)
The average number of MiBs per second that are transferred for read operations.
Write Data Rate (MiB/s)
The average number of MiBs per second that are transferred for write operations.
Total Data Rate (MiB/s)
The average number of MiB per second that are transferred for read operations and write operations.
Overall Read Cache Hit Percentage
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.
Write Cache Delay Percentage
The percentage of I/O operations that are delayed because of space constraints in the write cache, or because of other conditions. The value is a percentage of all operations.
This value applies only to resources that are running a version of IBM Storage Virtualize™ earlier than 7.3. The metric is an approximation because actual transfer rates are different for each cache layer. Therefore, you cannot directly compare this metric from resources that are 7.3 or later with earlier versions.
Processor Utilization Percentage
The average percentage of time that the processors on nodes are busy doing system I/O tasks. This value applies only to resources that are running IBM Storage Virtualize.

Related reports

To open related reports, click the name of the storage system and then click the name of the report. You can open the following related reports:

  • Performance of One Storage System
  • Most Active IO Groups