Host in maintainance mode extended period

[Phoung]

One of the Clusters I have inherited has had a host in maintenance mode for 6 months. I was told it was that to ensure there was some capacity available in case a lot of vms suddenly needed creating. The vcenter and hosts are esxi 5.5 Update2. The cluster is healthy except for a warning on the Cluster about a failed HA event awhile back during a network other when the hosts got confused. I read that warning only go away if turn HA on and off and it is cosmetic. Is it?

my actual question though is if it's safe to exit maintenance mode after such a long time?

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[cjscol]

Assuming host is configured correctly, e.g. has all the same networking as the other hosts in the cluster and can see all the same storage, then there should be no problem with exiting maintenance mode.

Even if some of these are wrong then exiting maintenance mode should not be an issue but you will not be able to migrate VMs to the host.