Array Firmware 3.2.0 through 3.2.6 May Cause Parity Mismatch on RAID 5 Volumes After Disk Replacement

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Array Firmware 3.2.0 through 3.2.6 May Cause Parity Mismatch on RAID 5 Volumes After Disk Replacement

1. Impact

After completion of the copy process to a standby disk triggered by a failing disk or a manually issued "vol disable to_standby" on a RAID 5 volume, either a "disk scrubber" task or a manually issued "vol verify" may detect parity mismatches on the standby.

2. Contributing Factors

This issue can occur on the following platforms:

SPARC Platform

• Sun StorageTek 6020, 6120, 6320, 6920 and T3+ with firmware versions 3.2.0 through 3.2.6

Notes:

1. The x86 platform is not affected by this issue.
2. This issue will only appear on a RAID 5 volume with the above listed arrays after a failing disk is copied to standby and the copy-back process has completed.

3. Symptoms

Following disk replacement, the copy-back process is started and completed. During the first "disk scrubber" task or a manually issued "vol verify", parity mismatches are reported in syslog, as in the following example:

    syslog: E: uXctr Vol verify detected data parity mismatch on Stripe: 0xXXXXXX

The parity information is not reliable until the "disk scrubber" or "vol verify" has recalculated the parity information for this volume. Parity mismatches only occur during the first "disk scrubber" task or manually issued "vol verify" after the copy to standby.

Note: If the first "disk scrubber" task or a manually issued "vol verify" has completed without error messages, the issue described has not occurred.

4. Workaround

To work around this issue:

1. After a failing disk has triggered a copy-to standby, abort the copy-to standby if it hasn't already finished.
2. Replace the failed disk so that a "parity reconstruct" is started.
3. If the copy-to-standby is finished, and a disk scrubbing task is not yet complete, abort the disk_scrubbing, pull the standby disk, and replace the failed disk so that a "parity reconstruct" is started.
4. Plug the standby disk back in.

Note: If the "disk scrubber" is disabled, "vol verify" should be run manually.

5. Resolution

This issue is addressed in the following release:

SPARC Platform

• Sun StorageTek 6020, 6120, 6320 and 6920 with firmware version 3.2.7 (as delivered in patch 116931-23 or later)

Please see the "Workaround" section to address this issue for the T3+.

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Modification History

16-Oct-2007: Updated Resolution Section
27-Oct-2008: No further updates needed, republish Resolved

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