Ps. Not sure why this didnt appear as a replym, but as a seperate thread. Apologies for that. Hey, Jose is right, you can do this via the api. The server needs to be shutdown. I usually use the below curl command on the engine itself (login with ssh). You need 3 pieces of information: - You need the ce.pem of the engine (which you can download from the engine login page) and make it available. In the command below I assume it is in the local directory. - You need an administrator user in engine, in the below example I used admin. Replace "yourpassword" behind the : with your own. - You need the disk-id as it is know in oVirt. You need to replace "yourdiskid", with your own. You can find the id in Engine. Select Storage, then Disks, then find the disk you want to convert and click on it. The number behind ID is the one you want and has the following format: db7b649f-76b6-4fd1-9b90-aa6becc2a283 The command: curl --cacert './ca.pem' --user 'admin@internal:yourpassword!' --request POST --header 'Version: 4' --header 'Content-Type: application/xml' --header 'Accept: application/xml' --data ' <action> <disk> <sparse>true</sparse> <format>cow</format> <backup_mode>incremental</backup_mode> </disk> </action> ' https://engine.blueit.dk/ovirt-engine/api/disks/yourdiskid/convert The command will return immediately. In engine you will see it is working on the disk image. You get the ballon messages in the right bottom corner and you can see it working in the taskview on the webinterface. Once it is done, you can start the VM again, and the disk is now thin provisioned and incremental backups are allowed. Good luck