Backup RHEV/RHV/ovirt disk image to external drive

Login to RHV/RHEV/ovirt administrator interface

Search for your VM, lets say I want to search for windows VM

Right click on the VM name, and choose 'Create Snapshot'

Give a proper name, and tick "Save Memory" if you want to save current state of memory as well. Please be warned, that by choosing "Save Memory", the VM will be paused while the snapshooting is in progress. 

If you check the Snapshots tab, the status of the snapshot will be Locked, and the VM will be paused

Once completed, the status will be changed to Ok

Now, open a terminal inside the rhev machine, and search for the disk image snapshot by running below command:

# virsh -r dumpxml windows | grep "source file"

Your newly created snapshot is on the last line of the above command. Copy the file location, and put it into your external drive

# cp /rhev/data-center/00000002-0002-0002-0002-00000000035d/747b7d84-68d5-4436-98f5-baeec68381e1/images/8af6c761-94ac-4adb-bf33-f009e3dd3dc7/../8af6c761-94ac-4adb-bf33-f009e3dd3dc7/../8af6c761-94ac-4adb-bf33-f009e3dd3dc7/../8af6c761-94ac-4adb-bf33-f009e3dd3dc7/../8af6c761-94ac-4adb-bf33-f009e3dd3dc7/e42c8e85-9566-4953-b881-70c7ce97de0b /mnt/my_external_drive/windows-snapshot-20181219.raw

If you want a different format, use qemu-img command to change it. For example, you require this image to be vmware compatible

# qemu-img -f raw -O vmdk /mnt/my_external_drive/windows-snapshot-20181219.raw /mnt/my_external_drive/windows-snapshot-20181219.vmdk