InstanceUUID and vMotion

Hi,

In my VM Backup application I have used instanceUuid of the VirtualMachine object to uniquley identify a VM. But going through the vStorageAPI documentation the recommended way is to use both UUID and the vmmoref to identify a VM. Why is that necessary?

Since I am referring the VM using instanceUUID, if a VM is moved to another ESX with vMotion, my backup application continues to work. But the application breaks if Stroage Vmotion is done to the VM. I understand a whole new VM is created during Storage Vmotion - which means a new UUID. Say if I manually update the stored UUID to the newly created one, would incremental backup continue to work(whether the ctk and delta files be intact during storage vmotion??)

Let me know your thoughts.

Thanks,

./Siva.