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When DNS is unavailable, how long NFS client will be able to access storage

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ontap-9
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nas
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Applies to

  • ONTAP 9.3 and later
  • CVO
  • NFS

Answer

  • There are two individual host caches; forward-lookup and reverse-lookup but the hosts cache settings are controlled as a whole. When a record is retrieved from DNS, the TTL of that record will be used for the cache TTL, otherwise, the default TTL in the host cache settings will be used (24 hours).
  • ONTAP 9.3 offers a new caching mechanism that moves name service caches out of memory and into a persistent cache that is replicated asynchronously between all nodes in the cluster.
  • If there is an entry in the cache, regardless if the entry’s TTL is expired or not, ONTAP will use that cache entry when external name services servers cannot be reached, thereby providing continued access to data served by the SVM.
  • If there is no entry in the cache, it denies access until DNS is available.

Additional Information

 

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