CONTAP-120558: Time to Live (TTL) of CNAME DNS record cached in ONTAP can be invalid
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 {color:#ffab00}100{color} 158.69 120.29 5.43 2299 10.26 34.39 553 28.15 9.93 839 0.00 .... . 0.00 .... .
0a.11.2 {color:#ffab00}100{color} 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 {color:#ffab00}22.22s{color} 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)