Road to Homelab: moving disks using qm command

I recently bought some new HDD’s, a much needed storage upgrade for my proxmox cluster, i’ve been running into storage issues in my current configuration. I’ve got a 1TB HDD that is hosting all my VM’s, LXC’s and images for my primary node. I’ve researched a few different ways to migrate VM’s from one physical storage to another, they all have their pro’s and con’s. For my particular use case i going to use a three stage method to migrate all my VM’s using the proxmox GUI and the QM command.

Concept of Operations (CONOP)

1. Move contents from current storage to an intermediate USB storage

   this is a necesary step because i don’t have an addtional SATA connector to plug additional storage into

2. validate the VM is working on the intermediate USB storage

   remove the old storage from the server

3. Setup new SATA based storage on server

   move VM’s from USB storage to SATA based storage

4. validate the VM is working on the new SATA based storage

Step 1

The command to move disks is the QM command

qm move_disk <vmid> <disk> <storage> [OPTIONS]

First thing with moving the storage, let’s navigate to the storage loction on the Proxmox node and take a look at our storage

cat /etc/pve/nodes/<node name>/qemu-server/<.conf file of VM>

Look at the output of CAT on the line for scsi0, most of the information needed is on that line

scsi0: local-lvm:vm-1070-disk-0,size=60G
  > 1070 is the VM ID
  > scsi0 is the disk you want to move

barra-usb-4tb-vm is the directory that the USB storage is configured under, this can be found from command line

type the following command:

cat /etc/pve/storage.cfg

the output of the command will be all the storage locations, below you can find the directory to move storage into under ‘dir:’

dir: barra-usb-4tb-vm
path /mnt/4tb-barracuda
content rootdir,images,vztmpl
nodes proxmox1
prune-backups keep-all=1
shared 0

Format, for this particular VM i want to change the format from RAW to qcow2, we can do this with the --format qcow2 option

The full command to move the vm is below:

qm move_disk 1070 scsi0 barra-usb-4tb-vm --format qcow2

After the move is complete, go back into the 1070.conf file and verify the move with two lines, the storage will change and unused storage will be the old storage

scsi0:barra-usb-4tb-vm:1070/vm-1070-disk-0.qcow2,size=60G
   
barra-usb-4tb-vm:1070/vm-1070-disk-0.qcow2,size=60G ___

Step 2

Once all the VM’s are moved over to the new storage and you are confident that everything is working, go into the Proxmox GUI and remove the volume group, in this case for myself it was 1tb-wd. If you receive a error or the GUI method will not work, try running lvremove -f /dev/<name of disk> and rerun the remove command.

Step 3

Setup your new HDD with the SATA connectors using the following steps:

First, identify the new HDD using the command lsblk, in my case this was sdc

Run the following command with parted, if you need to install parted run sudo apt install parted. You can use MBR as a partition table, GPT is a new and better standard so i’m using GPT.

parted /dev/sdc mklabel gpt

Now let’s make the primary partition using 100% of the disk.

parted -a opt /dev/sdc mkpart primary ext4 0% 100%

We have a partition now, sdc1, creating a file system is the next task with a volume label for future use since sdc is so generic

mkfs.ext4 -L wd-4tb /dev/sdc1

Run lsblk -fs to verify that the file system was created, the next step is to mount the drive on the server

Make a directory in the mnt directory mkdir -p /mnt/<folder name>

Edit the fstab so the file system will automount

open up fstab with a editor nano /etc/fstab then add a line LABEL=wd-4tb /mnt/wd-4tb ext4 defaults 0 2

mount -a

Step 4

Now, move the VM’s back into your storage attached to the server via SATA connectors. There are a couple of ways to move the storage.

1. Move using web GUI
2. Move via the command line

The web GUI might be the easier option and if you have a VM that is being stubborn and will not move via GUI, then use the command line, it is the same command qm move_disk that was used in STEP 1.

At this point, your HDD’s should be moved back to the new storage on your server, i’m going to use the USB for backups.

Cheers

Scott Powell

U.S. Army Officer specilizing in cybersecurity and IT Operations with 20+ years of experience, tech enthusiast with a passion for open-source, home lab and microservices