I am using XenCenter to access a XenServer with several VMs which I use for dev DBs. Periodically I create new VMs with a fresh batch of sanitized live data, then swap them out with the old VMs.

Normally in the New VM Wizard, for Storage, I disable the "Use storage-level fast disk clone" option to create a full copy of the virtual disks used in each VM. This time, however, I left the option checked. The new VM started up almost immediately, as expected.

I previously thought that the fast clone would link to the original only temporarily, while it did the full copy in the background. From some reading I've done today, it sounds like this is not the case; a fast clone is pretty much just a snapshot of the original plus a set of changes, and stays that way forever. (If I'm wrong, and the fast clone becomes a full copy on its own in the background, my question is irrelevant.)

In XenCenter, how can I convert a fast cloned virtual disk to a full copy?

2 Answers 2


I'm not sure this is the best way to go about fixing the problem but here is how I did it.

Export the VM you made a clone of, then delete the VM. This breaks the chain between the clone/parent, the clone will turn itself into a full copy.

Import the VM you deleted.


Yes you can. You need to use "xe vm-copy."

xe help vm-copy command name : vm-copy reqd params : new-name-label optional params : new-name-description, sr-uuid, description : Copy an existing VM, but without using storage-level fast disk clone operation (even if this is available). The disk images of the copied VM are guaranteed to be 'full images' - i.e. not part of a CoW chain. The simplest way to select the VM on which the operation is to be performed is by supplying the argument 'vm='. VMs can also be specified by filtering the full list of VMs on the values of fields. For example, specifying 'power-state=halted' will select all VMs whose power-state field is equal to 'halted'. Where multiple VMs are matching, the option '--multiple' must be specified to perform the operation. The full list of fields that can be matched can be obtained by the command 'xe vm-list params=all'. If no parameters to select VMs are given, the operation will be performed on all VMs.

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