[ovirt-users] production DC non responsive

Hi guys, good morning/night . first of all thanks to all the community and the whole team, you are doing a great effort . Today Im having an issue with ovirt 4.1.2 running as hosted engine over nfs. and data storage over iscsi. I found out of the problem when I tried to migrate one vm to another host and I got an error, so I powered off the vm's on that host and started them on the backup host with no problem, then I set the first host into mainteinance mode and after some minutes I restarted it(as usual). when it came back online, the whole dc turned RED as unavailable. can anyone please help me out? thanks, JP