[ovirt-users] Gluster command[<UNKNOWN>] failed on server ovhost1

Please help! I'm hosting an oVirt3.5 Engine server (CentOS6.5) and oVirt3.5 Host servers (CentOS 7.0). Today, I have stopped all oVirt services (ovirt-engine and vdsmd) and updated oVirt3.5 Engine server and ovirt3.5 Host server by "yum update". While update, some new Gluster components were installed. After update, I tried to reboot ovirt3.5 Engine and Node servers, but oVirt is not working. Portal's Events shows that: - Status of host ovhost1 was set to NonOperational. - Gluster command[<UNKNOWN>] failed on server ovhost1. My oVirt servers and VMs are not operational now. How to resolve? Many thanks, Fumihide Tani