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Why is there a delay in the output of the ls command on the origin side when the cache side is performing write operations?

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ontap-9
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nas
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Applies to

  • ONTAP 9
  • FlexCache

Answer

  • In a write-back FlexCache environment, the data that newly saved to Cache should be transferred to Origin volume.
  • After running ls command, Origin waits the Cache to complete the new data transferring, it takes time.

Additional Information

  • While a write is occurring on the cache side, if the ls is executed on the origin, it will reclaim the delegation from the cache, causing it to wait until the write-back is complete.
  • At that time, even if another ls is executed on the cache side, the delegation is in the process of being reclaimed on the origin side, and since the ls command has not yet been executed on the origin, the cache side has no choice but to wait.
  • As a result, after the write-back is completed, the delegation is reclaimed on the origin side, and the ls command is executed there.
  • Afterwards, the delegation is passed back to the cache side, where the ls command is then executed.
  • Although it may appear that ls commands are being executed simultaneously, in reality, the origin executes first, followed by the cache.

 

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