Who would like to be called during the midnight when you are having rest because of the system interruption due to hardware availability and etc. With high availability, user can continue to access the system without knowing there is a downtime happen. Look at the following configuration whereby you will see how to configure a high availability VM with the storage replication aka SteelEye. Once you have configure this, the VM can perform live migration or quick migration on a volume without any shared storage. The best practice is to have 1 VM per volume, which mean if your hyper-V host is loaded with the drive A(floppy Drive), C(system drive) and D(CD ROm), you just can host another 23 VM.