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High Network Processing (CPU N-blade) latency and poor performance due to locking

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Category:
ontap-9
Specialty:
nas
Last Updated:

Applies to

  • ONTAP 9.6 and newer
  • NFSv4

Issue

  • High latency is seen in Network column of qos statistics volume latency show
  • High locking rewinds are seen
    • Lock Open Owner is specific to NFSv4
Cluster::> set diag
Cluster::*> statistics start -object rw_ctx -counter nfs_rewinds
<wait 1 hour>
Cluster::*> statistics show -object rw_ctx -counter nfs_rewinds -value >1

Object: rw_ctx
Instance: rw_ctx
Start-time: 10/1/2021 21:37:16
End-time: 10/1/2021 22:37:16
Scope: node1

    Counter                                                     Value
    -------------------------------- --------------------------------
    nfs_rewinds                                                     -
                     Lock Open Owner                        229597544 <--over 60,000 per second
                     Lock Open State                            18610

Cluster::*>

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