CPU is higher than expected on idle NVMe-oF AFF systems
Applies to
- ONTAP 9
- All AFF systems with NVMe drives in NVMe over Fabrics (NVMe-oF) configuration
- All AFF systems with NVMe drives in NVMe over TCP (NVMe/TCP) configuration
Issue
- CPU may idle around 10% or 20% when clients are connected but there are 0 client IOPs
- Example: sysstat -m at node shell from A400 shows cores 0-14 at 0%, but 15-19 at 40% (some rows removed for readability):
Cluster::> node run -node <node> sysstat -m 1CPU15 CPU16 CPU17 CPU18 CPU19
  44%   38%   39%   41%   38%
  44%   37%   40%   42%   38%
  45%   38%   39%   44%   38%
  43%   37%   40%   41%   38%
  44%   37%   39%   41%   38%
  45%   45%   52%   46%   42%
  43%   37%   39%   42%   38%
  44%   38%   39%   40%   38%
  44%   41%   40%   41%   38%
  44%   38%   38%   41%   38%
