Add a thin provisioned logical volume to rescue a fulled Proxmox lab

It's a great & it's so efficient to have VM running on thin provisioned disks. However, I just learnt that Proxmox will quietly put a VM into some stalled status (web GUI shows a darkened icon but without green triangle, and the console will not respond) if the volume is fulled. Having Proxmox to reset or to boot with a .iso is possible, but sooner or later, all will hit the wall again.
I don't want to lose my VM, so my solution was to move a virtual disk out from the volume. I added a small USB drive (actually a mSATA SSD, seems performed ok) to the box, created a new thin pool volume, and move one VM out. Now I can keep the VMs running again.

Create a volume group on the USB (assuming a new group "external" on the disk /dev/sdc1):
vgcreate external /dev/sdc1 Create the volume (naming it "extdata") (yes, it's small):
lvcreate -L 14G -n extdata external Convert to a thin-provisioning volume:
lvconvert --type thin-pool external/extdata It's time to add the storage using web GUI (naming it "ext" here):
[WebGUI] > [Datacenter] > [Storage] > [Add] > ID: ext, Volume group: external, Thin pool: extdata > [Add] Finally, move the virtual disk: [WebGUI] > [999 (bustedVM)] > [Hardware] > [Hard Disk (virtio0)](the disk to move) > [Move disk] > Target storage: ext > [Move disk]