Try restarting libvirtd. It will also restart vdsmd, sometimes that fixes things for me when there has been a storage hiccup.
Thanks for the suggestion, but with the "ssh host restart" action actually the server has restarted completely, so I doubt it can be that
If it’s a HA Engine host, I’ve also had to restart the ha-agent/ha-broker combo is some situations as well.
No, it's an external engine
On the host:
[root@ov300 vdsm]# nodectl check
Status: OK
Bootloader ... OK
Layer boot entries ... OK
Valid boot entries ... OK
Mount points ... OK
Separate /var ... OK
Discard is used ... OK
Basic storage ... OK
Initialized VG ... OK
Initialized Thin Pool ... OK
Initialized LVs ... OK
Thin storage ... OK
Checking available space in thinpool ... OK
Checking thinpool auto-extend ... OK
vdsmd ... OK
[root@rhvh300 vdsm]#
I already had the idea to try restarting the engine server, and then I found this similar bugzilla (even if for an older release):
RHV host in "not responding" state until ovirt-engine service restarted
I rebooted the engine server (that is a VM inside a vSphere environment) and all came back good with the host set as up, together with the other ones.....
Gianluca