Am 2017-06-09 um 21:48 schrieb Karli Sjöberg:

Den 9 juni 2017 21:40 skrev Matthias Leopold <matthias.leopold@meduniwien.ac.at>:

hi,

i'm having trouble creating VM snapshots that include memory in my oVirt 4.1 test environment. when i do this the VM gets paused and shortly (20-30s) afterwards i'm seeing messages in engine.log about both iSCSI storage domains (master storage domain and data storage where VM resides) experiencing high latency. this quickly worsens from the engines view: VM is unresponsive, Host is unresponsive, engine wants to fence the host (impossible because it's the only host in the test cluster). in the end there is an EngineException

EngineException: org.ovirt.engine.core.vdsbroker.vdsbroker.VDSNetworkException: VDSGenericException: VDSNetworkException: Message timeout which can be caused by communication issues (Failed with error VDS_NETWORK_ERROR and code 5022)

the snapshot fails and is left in an inconsistent state. the situation has to be resolved manually with unlock_entity.sh and maybe lvm commands. this happened twice in exactly the same manner. VM snapshots without memory for this VM are not a problem.

VM guest OS is CentOS7 installed from one of the ovirt-image-repository images. it has the oVirt guest agent running.

what could be wrong?

Seems to me that the snapshot operation, where the host needs to save all of the VM memory chokes the storage pipe, the host becomes "unresponsive" from engine's point of view and all goes up shit creek. How is the hypervisor connected to the storage, in more detail?

/K

i shot myself in the foot by also playing around with network QoS and forgetting about it.... no wonder the network chokes when i tell it to do so. without randomly applied QoS profiles snapshots work perfectly ;-) thx matthias