VM compute resiliency: This will help providing resiliency to transient issues like a temporary disconnection of a cluster node due to some network issues or if the cluster service itself on the node crashes etc. The VMs will still continue working "Unmonitored" even if the node falls out of cluster membership into an isolated state. Here the unmonitored state of the VM implies that it is no longer monitored by cluster service. The default resiliency period is 4 minutes. This means the Unmonitored VMs will be allowed to run on that isolated node for 4 minutes and after that VMs will be failed over to a suitable node/ nodes in the cluster. And that particular node which is isolated is moved to a down state. The cluster service itself is now not a necessary dependency for a VM to run. As long as connectivity exists the VM will continue working.
Node quarantine: If a cluster node is isolated certain number of times (default is 3) within an hour it will be moved to quarantine state and the VMs running on it (if any) will be failed over to another suitable node/ nodes in the cluster.
Event 1 - cluster service stopped on node A - node A isolated (down) - cluster service restarted - node A online
Event 2 - cluster service stopped on node A - node A isolated (down) - cluster service restarted - node A online
Event 3 - cluster service stopped on node A - node A down - node A quarantined
The node will be quarantined for a period of 2 hours by default. But the administrator can manually start the cluster service on that node to join it back to the cluster.
VM storage resiliency: If there is a storage interruption, the VM identifies it and it will pause all the IO's for a certain duration and once the storage is available all IO operations will be resumed. This is very helpful in case of transient storage issues, saving the VM from blue screening or crashing. If the storage path is not back online after a certain period of time, it will pause the VM. Once storage comes back it auto resumes.
VM memory run time resize: You can now increase/ decrease RAM of a running VM.
Hot add/ remove VM network adapters: VM network adapters can also be added or removed on the fly.
Cluster OS rolling upgrades: With this feature you can upgrade your Hyper-V 2012 R2 cluster to Hyper-V 2016 cluster without shutting down the cluster. You can upgrade your existing cluster in 2 ways. Either you can add new 2016 nodes to the 2012 R2 cluster, migrate workload to new 2016 nodes and evict old nodes. Or you can evict one of the existing 2012 R2 node, do a clean installation of 2016, add it back to the cluster and do the same for rest of the nodes. Once all the nodes are 2016, you can update cluster functional level to 2016.
