I need to move a block device (Xen VM backing store) between sites with a minimum of downtime... my choices so far are: . dd - straightforward and foolproof but will take a while . dd + lvmsync (https://github.com/mpalmer/lvmsync) - untested but sounds plausible . drbd with external metadata - I already use drbd but haven't tried such a thing before I think drbd is going to be the best way to go, especially as it's part of Linux these days. My plan is: 1. Stop the VM 2. create the drbd metadata in a separate lv and initialise it all (without overwriting initial data!) 3. Start the VM 4. create the backing lv and metadata lv at the other site and configure drbd 5. Pick a low-usage time and kick it off then wait for completion 6. Stop the VM at the origin site 7. tear down DRBD 8. Start the VM at the new site Both sites are linked by openvswitch so they are effectively the same lan. Bandwidth is 20Mbits/second so it won't be lightning fast but the VM's are typically only 50GB in size which equates to around 7 hours + overheads. Any comments? I'm about to test with a small and unimportant VM. Thanks James