This is going to be a 5 part blog series.
What are these, why may I need it and how to configure it - in the context of Virtual Machine resources?
By default settings for all high available Hyper-V VMs are:
There are three advanced failover policies I can set up for my VMs. Let’s assume I have 4 nodes (Node1-4):
Preferred Owners - this is the preference of first node to run on - describes which node is the BEST for this particular VM. If I configure Node3-4 for my VM as preferred owner, any time the VM is on another node it will migrate back to Node 3 or Node 4. Fallback option configures if and when to fallback (see pics below).
Possible owners - this sets to which nodes a VM can failover. If I configure my VM with Node2-4 it won’t be able to migrate to Node1.
Anti-Affinity - this is the preference to keep similar VMs apart from each other. If I have my VM1 and VM2 hosting same role (think DC, or SQL cluster) I want to keep them off the same nodes. With this settings cluster will try to keep it that way. If VM1 is on Node1 and VM2 is Node3 and I will try to migrate VM1 to Best Possible Node, cluster service will try to migrate it first to Node2 or Node4 if possible. If not (i.e. lack of resources) it will be put on Node3
Possible owners is the
'hard set'. It will restrain VM from running on any other node. To configure this, VM has to be on one of
'possible owner' list first. I cannot set this to Node3 and Node4 if VM is on Node1 or Node2.
Let’s try to configure these options with GUI first.
Right clik on any VM and select Properties then I can check which nodes are considered ‘Preferred’
On the Failover tab I can set fallback policies
Select VM, on the Resources tab on the bottom right click on the Virtual Machine Name, select Properties:
On the Advanced Policies tab select which nodes are Possible. By default all are selected:
Let me give a few examples in which scenarios this can be usefull:
Stay tuned for next parts coming soon: