Cautions And Restrictions For Usage Statistics - HPE XP7 User Manual

Parity group monitoring
To correctly display the performance statistics of a parity group, all volumes belonging to
the parity group must be specified as monitoring targets.
Storage system maintenance
If the storage system is undergoing the following maintenance operations during monitoring,
the monitoring data might not be valid:
◦
Adding, replacing, or removing cache memory
◦
Adding, replacing, or removing data drives
◦
Changing the storage system configuration
◦
Replacing the microprogram
◦
Formatting or quick-formatting logical devices
◦
Adding, replacing, or removing MP blades
Storage system power-off
If the storage system is powered off during monitoring, monitoring stops until the storage
system is powered on again. Monitoring resumes when the storage system is powered on
again. However, Performance Monitor cannot display information about the period while the
storage system is powered off. Therefore, the monitoring data immediately after powering
on again might contain extremely large values.
Microprogram replacement
After the microprogram is replaced, monitoring data is not stored until the service engineer
releases the SVP from Modify mode. Therefore, inaccurate data might be temporarily
displayed.

Cautions and restrictions for usage statistics

Retention of short-range and long-range usage statistics
Usage statistics for the last six months (186 days) are displayed in long-range monitoring,
and usage statistics for up to the last 15 days are displayed in short-range monitoring. Usage
statistics outside of these ranges are deleted from the SVP. In short range monitoring, results
are retained for the last 1 to 15 days depending on the specified sampling interval. If the
retention period has passed since a monitoring result was obtained, the previous result has
been deleted from the SVP and cannot be displayed.
Statistics for periods of high I/O workload
For short-range monitoring, if the host I/O workload is high, the storage system gives higher
priority to I/O processing than to monitoring. If this occurs, some monitoring data might be
missing. If monitoring data is missing frequently, use the Edit Monitoring Switch window to
lengthen the sampling interval. For details, see
Volumes and CU ranges
The volumes to be monitored by Performance Monitor are specified by control unit (CU). If
the range of used CUs does not match the range of CUs monitored by Performance Monitor,
usage statistics might not be collected for some volumes.
Reverse resync operations
When you run the RAID Manager horctakeover command, the pairresync-swaps command
for a Cnt Ac-J pair, or the BCM YKRESYNC REVERSE command for a Cnt Ac-J MF pair,
12 Performance Monitor operations
"Starting monitoring" (page 14).