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What is the performance impact on NAS when using FPolicy in ONTAP?

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Category:
ontap-9
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nas
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Applies to

  • clustered Data ONTAP 8     
  • ONTAP 9 

Answer

  • FPolicy will cause CIFS and NFS work to be serialized (not spread across multiple processor cores). Look specifically at elevated Kahuna domain utilization with FPolicy enabled.
  • Prior to 9.2, NFS traffic will be impacted more than CIFS traffic, since there's no equivalent of first_read and first_write filter
     for NFS. This means that instead of just the first read operation being scanned, all packets for that read are scanned. (See Bug# 858682)
  • See KB Fpolicy EAGAIN errors seen in fpolicy.log for ways to detect and mitigate impact from overloaded FPolicy servers.
    Latencies and requests can be seen in Perfstat or via the CLI:
    • ONTAP:
      ::*> statistics start -object fpolicy -sample-id vserver
      ::*> statistics start -object fpolicy_policy -sample-id policy
      ::*> statistics start -object fpolicy_server -sample-id server

      ::*> statistics show -sample-id <sample-id_name> (will print output)

Additional Information

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