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CONTAP-120558: Time to Live (TTL) of CNAME DNS record cached in ONTAP can be invalid

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Issue

  • Disks will report 100% utilization and higher latency will be seen.
    • Could be a subset of disks or all disks on node.
      cluster::*> run -node node1 statit -b
      ... (wait 30 seconds)

      cluster::*> run -node node1 statit -e
      ...
      disk ut% xfers ureads-chain-usecs writeschain-usecs cpreads-chain-usecs greads-chain-usecs gwrites-chain-usecs
      /data_aggr1/plex0/rg0:
      0a.11.1 10 23.42 0.00 .... . 11.21 61.56 133 12.21 57.15 50 0.00 .... . 0.00 .... .
      0a.10.1 11 23.80 0.00 .... . 11.66 59.25 147 12.14 57.37 55 0.00 .... . 0.00 .... .
      1a.12.1 100 158.69 120.29 5.43 2299 10.26 34.39 553 28.15 9.93 839 0.00 .... . 0.00 .... .
      0a.11.2 100 156.09 118.85 5.39 2253 9.96 34.97 553 27.28 10.05 794 0.00 .... . 0.00 .... .

      cluster::> qos statistics volume latency show -vserver svm1 -volume vol1
      Workload         ID         Latency    Network    Cluster    Data         Disk    QoS Max   QoS Min     NVRAM 
       --------------- -------- --------- --------- --------- ------- ------ -----------  ----------- ----------
      total              -       4.71ms    185.00us      7.00us   468.00us     4.04ms  0ms        0ms        11.03s
      vol1-wid32140   32140   22.22s     86.00us    125.00us  904.00us 321.11ms  0ms        0ms        16.34s 
  • DNS TTL values may report incorrectly.
    • Azure best practice of page blobs is 60 second TTL.
      cluster::*> name-service cache hosts forward-lookup show vserver <cluster_name>
      (vserver services name-service cache hosts forward-lookup show)
      IP Address IP Create
      Vserver Host Protocol Family Address Source Time TTL(sec)
       --------- -------- -------- ------- -------------- ------- ---------- --------
      cluster pageblobhost.blob.core.windows.net Any Ipv4 dns 53050
      20.1.2.3 11/28/2023 09:22:43
      cluster pageblobhost.blob.core.windows.net Any Ipv4 dns 25462
      20.1.2.3 11/28/2023 09:26:40
      ...
      Note: Make sure the SVM name matches cluster name before the prompt (::*> in this case)

 

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