HP XP RAID Manager Software - Manual (Page 18)

Cautions and restrictions for usage statistics
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Usage statistics for the last three months (93 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 storage system.
•
In the short range, monitoring results are retained for the last 8 hours to 15 days depending
on the specified gathering interval. If the retention period has passed since a monitoring result
was obtained, the previous result has been deleted from the storage system and cannot be
displayed.
•
When the monitoring switch is set to disabled, no monitoring data is collected. This applies
to both long-range and short-range data.
•
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 Time Range option to lengthen
the collection interval. For details, see
“Starting monitoring” (page 28) .
•
The monitoring data (short-range and long-range) may have a margin of error.
•
If the SVP is overloaded, the system might require more time than the gathering interval allows
to update the display of monitoring data. If this occurs, some portion of monitoring data is
not displayed. For example, suppose that the gathering interval is 1 minute. In this case, if
the display in the Performance Management window is updated at 9:00 and the next update
occurs at 9:02, the window (including the graph) does not display the monitoring result for
the period of 9:00 to 9:01. This situation can occur when the following maintenance operations
are performed:
◦ Adding, replacing, or removing cache memory.
◦ Adding, replacing, or removing data drives.
◦ Changing the storage system configuration.
◦ Replacing the microprogram.
•
Pool-VOLs of Fast Snap, Snapshot, Thin Provisioning, and Thin Provisioning Z are not monitored.
NOTE: When you run the RAID Manager horctakeover or pairresync-swaps command for a Cnt
Ac-J pair or the BCM YKRESYNC REVERSE command for a Cnt Ac-J Z pair, the primary and
secondary volumes are swapped. You can collect the before-swapped information immediately
after you run any of the commands. Incorrect monitoring data will be generated for a short time
but will be corrected automatically when the monitoring data gets updated. The incorrect data will
also be generated when the volume used for a secondary volume is used as a primary volume
after a Cnt Ac-J or Cnt Ac-J Z pair is deleted.
Using Performance Control
•
Starting Performance Control. Ensure that the Time Range in the Monitor Performance window
is not set to Use Real Time. You cannot start Performance Control in real-time mode.
•
I/O rates and transfer rates. Performance Control runs based on I/O rates and transfer rates
measured by Performance Monitor. Performance Monitor measures I/O rates and transfer
rates every second, and calculates the average I/O rate and the average transfer rate for
every gathering interval (specified between 1 and 15 minutes) regularly.
Suppose that 1 minute is specified as the gathering interval and the I/O rate at the port 1-A
changes as illustrated in Graph 1. When you use Performance Monitor to display the I/O
rate graph for 1A, the line in the graph indicates changes in the average I/O rate calculated
every minute (refer to Graph 2). If you select the Detail check box in the Performance Monitor
18 Interoperability of Performance Monitor and other products