We have been experiencing an ongoing issue where VM's are not migrated to a new host during an HA event. Here are our current cluster settings:
Admission Control is set to Disable
VM restart priority is set to Medium
Host Isolation response is set to Leave powered on
The hosts are 4.1, within a 5.0 vCenter. We do have enough failover capacity for a single host failure. The problem we have is if a host with 5 VM's has a host failure (hardware or other), 3 of the VM's will migrate to a new host without issue. The remaining 2 VM's do not migrate, and are left in a powered off state until they are manually powered back on.
Not sure if it is relevant or not, but one key difference in the VM's that do and do not failover are the ones that do not failover are configured to use RDM's.
Is there any reason why some VM's would migrate fine, while others will not? Is there anything we can check out? Thank you in advance.