Q: I can't use System Center Virtual Machine Manager to make a virtual machine highly available after it has already been deployed to a host. What should I do?
A: When you use System Center Virtual Machine Manager to deploy a virtual machine, one option is to make the virtual machine highly available. This will result in the virtual machine being stored on clustered storage, and only hosts in the cluster will be available as a target for the virtual machine deployment. If you initially deploy a virtual machine as not highly available, but it's still deployed to a host in a cluster and is still stored on clustered storage, you might think it will be simple to make the virtual machine highly available. However, when you stop the virtual machine and try to modify its properties, the high availability property is grayed out, as in the following figure.
This is because once the virtual machine is deployed, this property becomes read only and the virtual machine cannot be made highly available in this way. The solution is to perform a migration of the virtual machine by selecting the Migrate Virtual Machine option, as the following figure shows.
In the main migration dialog box, make sure you select Make this VM highly available, as the following figure shows, and select a target node. You must select a different node from where the virtual machine is currently deployed, but the target node can be in the same cluster as the node on which the virtual machine currently resides.
Once the virtual machine migration is complete, the virtual machine will be highly available.