View source for Qemu-img Differences between Snapshots

=Internal=

* [[Qemu-img#List_Differences_between_Snapshots|qemu-img]]

=Overview=

This is a procedure that can be used to list differences between [[qemu-img]] snapshots. It is probably not optimal, and there are probably tools that do this better, but at the time of the writing, I did not know about them.

=Procedure=

1. Take a snapshot of the filesystem ''before'' the event whose effects you want to analyze: [[Qemu-img#Take_a_Snapshot|qemu-img snapshot -c ...]]

2. Trigger the event.

3. Save the state of the filesystem after the event, by cloning the filesystem, with [[Virsh vol-clone|virsh vol-clone]], after the VM guest has been shut down:

 virsh vol-clone --pool main-storage-pool --prealloc-metadata build-guest.qcow2 build-guest-after.qcow2

4. Revert the original filesystem to the state before the event, by reverting to snapshot, with [[Qemu-img#Revert_the_Disk_to_a_Saved_State|qemu-img snapshot -a <''snapshot-tag''> <''volume-name''>]]