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

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ontap-9
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NAS
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Issue

  • Disks may have higher utilization and latency due to this.
    • DNS TTL values may report incorrectly.
    • Azure best practice of page blobs is 60 second TTL.
  • Disks will report 100% utilization and higher latency will be seen.
    • Could be a subset of disks or all disks on node.


::cluster::> set -privilege advanced
::
::Warning: These advanced commands are potentially dangerous; use them only when directed to do so by NetApp personnel.
::Do you want to continue? {y|n}: y
::
::cluster::*> name-service cache hosts forward-lookup show -vserver <cluster_name> <--Make sure the SVM name matches cluster name before the prompt (::*> in this case)
::  (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
::...
::cluster::*> run -node node1 statit -b
::... (wait 30 seconds)
::cluster::*> run -node node1 statit -e
::...
::disk             ut%  xfers  ureads--chain-usecs writes--chain-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

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