Cautions and restrictions for usage statistics

Usage statistics for up to the last 15 days are displayed in monitoring. Usage statistics outside of these ranges are deleted from the SVP.

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 Starting monitoring.

When you run the CCI horctakeover command, the pairresync-swaps command for a UR pair, the primary and secondary volumes are swapped. You can collect the before-swapped information immediately after you run any of the commands. Invalid monitoring data will be generated for a short time but will be corrected automatically when the monitoring data gets updated. The invalid data will temporarily be generated when the volume used for a secondary volume is used as a primary volume after a UR pair pair is deleted.

Monitoring data cannot be displayed within the first two sampling intervals after the monitoring starts or the sampling interval is changed because no monitoring data has accumulated. For instance, if the sampling interval is set or changed to 15 minutes, monitoring data is not accumulated for up to 29 minutes after this setting is made.

If the SVP is overloaded, the system might require more time than the sampling interval allows to update the display of monitoring data. If this occurs, a portion of monitoring data is not displayed. For example, suppose that the sampling interval is 1 minute, and the display in the Performance Management window is updated at 9:00 and the next update occurs at 9:02. In this case, 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 on the storage system or on the Device Manager - Storage Navigator PC:

• Adding, replacing, or removing cache memory.
• Adding, replacing, or removing data drives.
• Changing the storage system configuration.
• Replacing the firmware.

Pool-VOLs of Thin Image, Dynamic Provisioning, are not monitored.

The monitoring data might have a margin of error.