How to move a raw disk image from LVM-thin storage in Proxmox

Moving a raw disk image from LVM-thin storage in Proxmox is straightforward with qm move-disk, but sometimes you need the manual path. Here’s how to do both, and when each makes sense.

Use qm move-disk for most cases

The built-in command handles the whole move, including format conversion if the target storage needs it. For VM 100, moving disk scsi0 to local-lvm (which is also LVM-thin) is just:

qm move-disk 100 scsi0 local-lvm

If the target is a directory storage like local, Proxmox will convert the raw image to qcow2 automatically. You can force a format with --format qcow2 if needed. The VM can stay running during the move, but I’d shut it down first—it’s less likely to cause weirdness with active writes.

Manual copy when qm move-disk won’t work

Sometimes the command fails, or you want to move the disk to a storage Proxmox doesn’t know about. LVM-thin volumes live under /dev/mapper/, so you can copy them with dd or qemu-img. First find the volume path:

lvdisplay | grep -A5 "LV Name.*vm-100-disk-0"

Then copy it to a file on the target storage:

qemu-img convert -O qcow2 /dev/pve/vm-100-disk-0 /mnt/target/vm-100-disk-0.qcow2

This converts the raw LVM-thin volume to qcow2 in one step. If you want to keep it raw, use dd if=/dev/pve/vm-100-disk-0 of=/mnt/target/vm-100-disk-0.raw bs=4M status=progress. Note that dd copies the full allocated size, not just the used space—thin provisioning is lost. qemu-img convert is smarter and only writes actual data.

After the move

Detach the old disk from the VM and attach the new one. In the web UI, remove the old scsi0, then add a new disk pointing to the copied file. Or edit the config directly:

nano /etc/pve/qemu-server/100.conf

Change the scsi0: line to the new storage and filename. Then start the VM and make sure it boots.

If you’re moving to NFS or another shared storage, check out Proxmox shared storage NFS for the right mount options.

Which method should you use?

qm move-disk is the safe default. It preserves thin provisioning when possible, handles format conversion, and updates the VM config for you. Manual copy is for when you need to move the disk to a non-Proxmox location, or when the command fails for some reason. In that case, qemu-img convert is better than dd because it respects thin provisioning and gives you format control.

One more thing: if you’re moving a disk with snapshots, qm move-disk will fail unless you use --delete to remove snapshots first. Manual copy doesn’t care about snapshots, but you’ll lose them anyway—so plan accordingly.