Symptoms:
When creating or reverting snapshots, you will see this error message below.
"There are currently X usable fault domains. The operation requires X more usable fault domains."
Example:
24-node Cluster with 3 Fault Domains (= 8 Hosts per FD).
1.) All Hosts in one Fault Domain are being shut down.
2.) You are trying to revert a Snapshot of one VM and receiving the error message:
"An error occurred while reverting to a snapshot: Out of resources.
"There are currently 2 usable fault domains. The operation requires 1 more usable fault domains."