vMotion ends in “Cannot connect to host”

Recently I entered a problem when trying to migrate VMs to new hosts and storage. vMotion in new environment was already running without problems. After changing vMotion configuration in new environment to enable migration from existing host, I got an error when trying to migrate using storage vMotion. The error was: “Cannot connect to host”. The vMotion task ended a second after start. Source host didn’t show any entry in vmkernel.log. It appears, vCenter didn’t even try to connect a host.

Fortunately, solution is quite simple: re-add target-host to vCenter. To do so without shutting down or moving any VM you can:

1. Disconnect host from vCenter
2. Remove host from inventory
3. Add host to vCenter and cluster again

It appears vCenter did not recognize changes in vMotion configuration. With re-adding host, vCenter gets new settings. Maybe there is a better way?

A downside of this procedure is that each VM of this host will get a new ID generated by vCenter. So each software that uses this ID will recognize VMs as new VMs. For example you will probably get a full as next backup.