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Hitachi Vantara Knowledge

Removing a single mirror relationship

This procedure is useful for replacing a failing secondary SD. Coupled with a clean failover and failback, it can also be used to replace a failing primary SDs without data-loss.

To remove a single mirror relationship


  1. Use the sd-span-cod-reads command to instruct the server not to load the on-disk configuration. This prevents severe events being logged when the mirror relationship is broken.

  2. Use the sd-mirror S P=none command (where S is the span's instance name and P is the device ID of the P-Vol), to instruct the server to remove the S-Vol from the span.

  3. Use your storage configurator to break the mirror relationship.

  4. Do one of the following:

    • Use your storage configurator to delete the failing SD, and then use the sd-forget command to remove it from the registry.
    • Use the sd-deny-access command to unlicense the failing SD.
    • Use the sd-wipe-cod-signature command to erase the Cod signature on the failing SD.
  5. Use the sd-span-cod-reads --resume to tell the server to resume loading the on-disk configuration. It is usual to set up a new mirror SD and then use either the sd-mirror-prepare and sd-mirror-detect commands or the sd-mirror command in order to incorporate it into the span, as detailed above.


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