Verifying Units

For redundant units, verify checks the redundancy of the unit. For example it will check parity for a RAID 5 or check data consistency for a RAID 1. If the unit you checked is not a redundant unit, verify performs a surface scan of the media. During verification, I/O continues normally, but with a slight performance loss, depending on your verify rate setting. For more details about how verification works, see About Verification. For details about verify rates, see Setting Background Task Rate.

For 9000 series controllers, if the verify unit process determines that the mirrored drives are not identical or the parity is not correct, the error is corrected. For RAID 1 and 10, this involves copying the miscompared data from the lower port(s) to the higher port(s) of the mirror. For RAID 5 this involves recalculating and rewriting the RAID 5 parity that was incorrect. AEN 36 ("Verify detected and fixed data/parity mismatch") is posted to the Alarms page.

When this occurs for 7000/8000 series controllers, AEN 36 ("Verify detected and fixed data/parity mismatch") is logged and the entire unit is initialized. For RAID 1 and 10, initialization involves copying the data from the lower port(s) to the higher port(s) of the mirror. For RAID 5 this involves recalculating and rewriting the RAID 5 parity for the entire unit. If the unit is not redundant, a file-system check is recommended to correct the issue. If the errors persist and cannot be overwritten from a backup copy, perform a final incremental backup. You will need to replace the defective drive, recreate the unit, and reinstall the data.

Note: If the unit has not previously been initialized and you manually select Verify Unit in either the initialization process starts.

Verification of units can be done automatically, on a schedule, or can be started manually, as described below. For information about scheduling, see Scheduling Background Tasks.

You can manually start a verify.

To verify a unit

In 3DM, choose Management > Maintenance.
In the Unit Maintenance section of the Maintenance Page, select the unit you want to verify and click Verify Unit.

3DM puts the selected unit in verifying mode. If verify scheduling is not enabled on the Scheduling page, the verification process begins almost immediately. If verify scheduling is enabled, the unit will not start actively verifying until the next scheduled time.

A Stop Verify link appears next to the unit on the Maintenance page. If you need to stop the verify process, use this link. (If initialization starts because the unit had not previously been initialized, it cannot be halted, so no Stop Verify link appears.)

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