In recent days, a customer reported an anomaly on an HPE SimpliVity cluster hosting instant clone Horizon VDIs. In detail:
- vSphere with seven hosts present, two were always at 98% CPU utilization and 90% RAM utilization.
- Continuous vMotion generated by the VM DRS to and from those two HOSTS.
After a careful analysis, we identified that there were no problems at the vSphere infrastructure level.
The issue was due to a Simplivity feature called IWO.
By disabling IWO and keeping DRS active (Full automatic) I have an optimal balance of CPU and RAM load between hosts at the expense of a slight increase in I/O trip times
Scenario – Even VM Load Distribution
I want even VM load across my cluster in terms of CPU and memory. Data locality and I/O performance are not top priorities. Most applications are CPU and memory intensive, and adding 1ms to 2ms to I/O trip times will not impact application performance.
In this scenario, IWO can be disabled thus ensuring no DRS affinity rules are populated into vCenter server. Suppressing DRS affinity rules will allow VMware DRS or allow you to directly distribute VMs across the cluster as desired to ensure all VMs are adequately resourced in terms of CPU and memory. The ‘Data Access Not Optimized’ alarm can be suppressed within vCenter server.