Cloud Volumes ONTAP: High CPU utilization on highest-numbered CPU of Azure HA nodes

Applies to

Cloud Volumes ONTAP(CVO)

Issue

In an Azure high-availability (HA) configuration, the highest-numbered CPU might operate at or around 100% CPU utilization, even when the Azure CVO is idle or only  serving a small number of client IOPS.

cluster::> set diag
cluster::*> node run -node cluster-01 sysstat -M -c 3 1
ANY1+ ... ANY16+  AVG CPU0 CPU1 CPU2 CPU3 CPU4 CPU5 CPU6 CPU7 CPU8 CPU9 CPU10 CPU11 CPU12 CPU13 CPU14 CPU15 Nwk_Lg ...
100%         0%   9%   3%   3%   2%   3%   2%   2%   2%   2%   3%   3%    3%    3%    2%    2%    3%  100%     0%
100%         0%  12%   7%   5%   6%   5%   5%   6%   5%   5%   6%   6%   11%    6%    5%    6%    7%  100%     0%
100%         0%   8%   1%   1%   1%   1%   1%   2%   1%   2%   1%   1%   11%    1%    5%    1%    1%  100%     0%

Notes:

• This example shows a configuration with 16 CPU cores.
• CPU15 is constantly 100% utilized without any real user workload.
• The command output above is truncated to just highlight the high CPU utilization of the last CPU core(CPU15).