[ovirt-users] hosts becomes NonResponsive

Hi, time to time one of our four ovirt hosts become NonResponsive. From engine point of view it looks this way (engine.log) 2019-05-21 13:10:30,261+02 ERROR [org.ovirt.engine.core.dal.dbbroker.auditloghandling.AuditLogDirector] (EE-ManagedThreadFactory-engineScheduled-Thread-95) [] EVENT_ID: VDS_BROKER_COMMAND_FAILURE(10,802), VDSM ovirt03.net.slu.cz command Get Host Capabilities failed: Message timeout which can be caused by communication issues 2019-05-21 13:10:30,261+02 ERROR [org.ovirt.engine.core.vdsbroker.monitoring.HostMonitoring] (EE-ManagedThreadFactory-engineScheduled-Thread-95) [] Unable to RefreshCapabilities: VDSNetworkException: VDSGenericException: VDSNetworkException: Message timeout which can be caused by communication issues from host (which is reachable) it looks like (vdsm.log) 2019-05-21 13:10:27,154+0200 INFO (vmrecovery) [vdsm.api] START getConnectedStoragePoolsList(options=None) from=internal, task_id=a1bebf2f-7070-4344-90b7-1d709ba94b5c (api:48) 2019-05-21 13:10:27,154+0200 INFO (vmrecovery) [vdsm.api] FINISH getConnectedStoragePoolsList return={'poollist': []} from=internal, task_id=a1bebf2f-7070-4344-90b7-1d709ba94b5c (api:54) 2019-05-21 13:10:27,155+0200 INFO (vmrecovery) [vds] recovery: waiting for storage pool to go up (clientIF:709) 2019-05-21 13:10:31,245+0200 INFO (jsonrpc/4) [api.host] START getAllVmStats() from=::1,39144 (api:48) 2019-05-21 13:10:31,247+0200 INFO (jsonrpc/4) [api.host] FINISH getAllVmStats return={'status': {'message': 'Done', 'code': 0}, 'statsList': (suppressed)} from=::1,39144 (api:54) 2019-05-21 13:10:31,249+0200 INFO (jsonrpc/4) [jsonrpc.JsonRpcServer] RPC call Host.getAllVmStats succeeded in 0.00 seconds (__init__:312) hosts are latest CentOS7 (but old AMD Opteron HW), oVirt is 4.3.3.7-1.el7 I cannot track it down to network layer. We have 4 other RHV hosts on the same infrastructure and it works well. Some clues what is happening? Thanks in advance, Jiri Slezka