I Have single drive for my main proxmox node. It has all VM’s disks. Separate hardware raid has proxmox install.

Try first in a VM before proceeding. I mainly created this for my self, when I tried this in a VM. Yet to be done in practice in production.

Plug your new drive in and reboot node.

Setup disk

Go to: Node -> Disks -> ZFS
Make a ZFS pool with that single drive.

Thin provisioning can be enabled in Datacenter -> Storage
Edit the storage and enable Thin provisioning.

Migrate VM’s & CT’s

Move all hosts to the new Drive. Probably recommended Delete source is checked.

VM: Hardware -> Hard Disk
Select the drive you want to move -> Disk Action -> Move Storage

CT: Resources -> Root Disk
Select the drive you want to move Volume Action -> Move Storage

We can check on the drive we migrated from, is everything is migrated.

Raid time

Go to Node -> Disks -> LVM
Select the Storage you moved everything off of -> More -> Destroy

Datacenter -> Storage
Select the Storage you moved everything off of -> Remove

Now SSH, in to your server

You will need the disk id’s of the zfs storage and the disk we deleted.
Basically # zpool attach <pool> <current-disk-id> <new-disk-id> To make a mirror raid.
You can get the id of your drive with ls -l /dev/disk/by-id/
Also will need the current disk, can be show with zpoll status <pool>

Sources

ZFS single-disk to mirror
https://askubuntu.com/questions/1301828/extend-existing-single-disk-zfs-with-a-mirror-without-formating-the-existing-hdd

Proxmox ZFS thin-provisioning
https://forum.proxmox.com/threads/zfs-enable-thin-provisioning.41549/