Mastering Proxmox - Third Edition

Loss of connectivity between Proxmox and storage nodes

If the network connectivity between Proxmox nodes and storage nodes is lost, users will experience a frozen state in their VMs. If the connection is stored within a reasonable amount of time, the VM will resume operation. If the connection is not restored after an extended amount of time, the VM will need to be restarted after the connection is restored. The reason VMs can continue operating after the connection is restored is that VM data remains in the memory, which is not directly affected by the storage node. 

Usually, network connectivity affecting multiple nodes can be traced down to a physical network switch, while a single node network connectivity loss is due to the node itself ...