When the performance monitoring switch is set to disabled, monitoring data is not collected.

If the SVP time setting is changed while the monitoring switch is enabled, the following monitoring errors can occur:

• Invalid monitoring data appears.
• No monitoring data is collected.

If you have changed the SVP time setting, disable the monitoring switch, and then re-enable the monitoring switch. Next, obtain the monitoring data. For details about the monitoring switch, see Starting monitoring.

About the traffic monitoring between host bus adapters and storage system ports in Performance Monitor

You must configure some settings before the traffic between host bus adapters and storage system ports can be monitored. For details, see Adding new WWNs to monitor, Adding WWNs to ports, and Connecting WWNs to ports.

To correctly display the performance statistics of a parity group, all volumes belonging to the parity group must be specified as monitoring targets.

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 firmware
• Formatting or quick-formatting logical devices
• Adding, replacing, or removing MP unit

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.

After the firmware is replaced, monitoring data is not stored until the service engineer releases the SVP from Modify mode. Therefore, inaccurate data might be temporarily displayed.