The goal of the steps below is to resize (shrink) the ext4 partition /dev/sda2 and its disk /dev/sda below to 6.9T, so that they fit within the thin-LVM pool sized at 6.95T
Disclaimer: I have no idea what I’m doing, so follow these steps at your own risk.
1. Trim Unused Space
Inside the VM, run:
fstrim -a
This will save time during the disk operations.
2. Boot into GParted Live ISO
Boot the VM using the GParted Live ISO.
3. Resize the Partition
Use the GParted GUI to shrink the partition /dev/sda2 to the smallest size possible, leaving a little headroom.
Example:
4. Shutdown the VM
After resizing, the partition /dev/sda2 will now be smaller, but the disk itself (/dev/sda) will still be the original size. Let’s fix that. Shut down the VM.
Example:
5. Resize the Disk on the Proxmox Host
On the Proxmox host (hypervisor), resize the VM disk to fit within the thin-LVM pool:
lvreduce -L 6.9T /dev/media/vm-101-disk-0
Replace /dev/media/vm-101-disk-0 with your VM’s disk path.
Why 6.9T? My thin-LVM is 6.95T, so I left a bit of headroom to avoid overcommitting the pool.
Example:
6. Rescan the Disk in Proxmox
Run the following to make Proxmox aware of the new disk size:
qm rescan
Example output:
7. Attempt to Boot the VM
If you’re lucky, the VM will boot without issues. However, you’ll most likely encounter an error like:
ALERT! /dev/disk/by-uuid/xxxxxxxxx does not exist. Dropping to a shell
If this happens, boot the VM into the GParted Live ISO again. The GParted GUI will show all storage as unallocated, but don’t panic (famous last words).
Example:
8. Fix Partition Errors with gdisk
Open a terminal in GParted and run:
sudo gdisk /dev/sda
- Type
vto verify the disk. - You’ll likely see warnings or errors. Follow the on-screen instructions to fix them.
- For example, I had to go to the expert menu (
x), then presse, and so on, until all errors were resolved.
- For example, I had to go to the expert menu (
- Once everything is fixed, type
wto write the changes to the disk and press Enter.
Example:
9. Resize the Partition Back to Match the Disk
Open the GParted GUI again. This time, you can expand the partition to fill the resized disk.
Example:
10. Verify the Disk Layout
Check that the disk size and partition size match your desired configuration:
sudo fdisk -l
Example:
11. Check the Filesystem for Errors
Run a filesystem check to ensure no errors:
e2fsck -f /dev/sda2
12. Reboot the VM
Finally, reboot the VM. It should boot without any issues, and the disk and partition should now be sized as desired.
Example:
That wasn’t so hard after all… lol. I hope it helps