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What is a persistent cache backup device failure?

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Applies to

All E-Series platforms

Answer

If a diagnostic test for a persistent cache backup device fails, then the device is considered unusable. All volumes will change to write-through caching whenever the usable capacity of the persistent cache backup device is less than that of the cache memory. 

  • This will generate a recovery failure entry stating that there is insufficient cache backup device capacity
  • Volumes configured to allow write caching without batteries will be unaffected

Note: It is possible (although unlikely to occur) that losing a persistent cache backup device will not cause the usable capacity of persistent storage to fall below the usable capacity of cache memory. In this case, cache will be unaffected.

Additional Information

Replacement of the controller posting the error will be necessary to resolve the issue.

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