Force provisioning is essential for each storage policy that uses all hosts?

[pvlasek]

Otherwise snapshot (and dependent replication, backup, ...) fails in the case of planned maintenace of one host.

Example: 5 hosts, VM with storage policy: failures = 2, 1 host in maintenance mode (installing patches / bios update / ...)

Attempt to create snapshot:

- @vSphere Client:

An error occurred while taking a snapshot: msg.disklib.FILENOTFOUND.

An unknown error has occurred.

- @Web Client:

An error occurred while taking a snapshot: The system cannot find the file specified.

The policy requires 5 hosts contributing storage, only found 4 in the cluster.

As storage policy for snapshot is inherited from parent disk, policy for whole VM has to include: force provisioning = yes.

Or I misunderstood something?

[CHogan]

Please have a quick read of this post - VSAN Part 25 – How many hosts needed to tolerate failures? | CormacHogan.com

In order to tolerate 2 failures, you need a minimum of 5 ESXi hosts contributing storage.

Snapshots inherit the same policy as the VMDK, so they will also need 5 hosts.

Because you have only 4 hosts available, as one is in maintenance mode, you cannot deploy VMs with this policy, nor can you take snapshots of existing VMs.

That is why you need to use force provision - this will deploy the VMs even though the VMs will be non-compliant (their policy requirements cannot be met). It will also allow snapshots to be taken as you observed.

When the 5th host is added back into the cluster (maintenance mode exited), the VMs and the snapshots should reconfigure and go compliant.

You should also be able to take snapshots without the need to force-provision.

VSAN is behaving exactly as designed in this case.

HTH

Cormac