thanks for your response.

i understand. But yesterday happened this on one of cluster that was off for a long time: router could not assign same ip and assigned another IP and all went well - cluster is up, gluster with briks is ok (gluster is configured with another internal network).

Which mechanism made ip of ovirtmgmt change in this case? 

Is it possible simply change dhcp parameters on router and assign by MAC new ip? 

 Thanks again