@Greg_E "if that host crashes" -- that's the problem. When the host is gone, VMs are gone. Not colored in red 'we are gone', there are none of them.
There is no problem running XO itself on other host.
The question is not how to keep VMs backed -- they are.
But right now, when host X is gone and its VMs are replicated to hosts Y and Z, how can i quickly see that VMs A,B,C and D are gone and E, F, G, etc are up? No way, because X is gone and its VMs gone too.
I have to monitor them via Zabbix to see if they are gone.
But syncing hundreds of VMs with Zabbix is tiresome, it's a lot of manual work.