Ovirt 3.4.3-1: recover VM from an "unknown" state.

After iscsi(iser) storage failure and host local disk corruption one of the HA VMs is stalled in "?"=status unknown. restarting ovirt-engine and hosts did not help much. The host which was owning VM was not there. But Web portal was showing unknown status for the host. I was not able to reboot or stop it. All services are gone with bad disk on the host. Looks like main problem was missing iscsi disk storage. It was hanging in "locked state". I found simple solution in 3 steps:

1. find the hanging disk ID from web interface it looks something like this:324f9089-0a40-4744-aa33-5c5a108f7f43

2. on ovirt-engine server: su - postgres

3. psql -U postgres engine -c "select fn_db_unlock_disk('324f9089-0a40-4744-aa33-5c5a108f7f43');"

   After this steps take down hanging host from the web interface. HA VM will come up to another "healthy node".