Symptoms
Snapshot Consolidation fails and causes the Host to go unresponsive. In the Hostd logs you see entries similar to:
2021-10-07T21:06:04.828Z warning hostd[2515463] [Originator@6876 sub=IoTracker] In thread 2515941, preadv("/vmfs/devices/vdfm/1088ff3-vdfm") took over 840 sec.
The ESXi Host is on ESXI 7.0U2 or above. An SIOC policy is used on the VM being consolidated with shares at or below 400.
Impact / Risks
After upgrade to ESXi 7.0U2 or above, environments that utilise limits/shares below 400 on SIOC policies will begin to see consolidation tasks that cause the Host to go into a hung state.
Resolution
This issue is resolved in vSphere ESXi 7.0 U3l (build number 21424296).This issue is resolved in vSphere ESXi 8.0b (build number 21203435).
Workaround
To resolve the unresponsive Host, rebooting the Host is the only workaround at this time.Disabling SIOC policies on the VMs, or increasing the Shares and Limits will allow consolidation to work. It has also been seen that cloning the VM in question resolves the issue. On top of this;
The issue is not seen when SPM is disabled.The issue is not seen with policies with higher limits such as Gold or even when the Lead policy is reapplied.
