Reducing lxc size in Proxmox

Sometimes there comes a moment when a container in Proxmox becomes uselessly large and its size needs to be reduced. In this article I will tell you how to do it.

Reducing disk size

Important: Before reducing the disk size, make sure to make a backup of the container!

1. First we need to find the disk what we need, you can use the command

lvdisplay | grep "LV Path\|LV Size"

  LV Path /dev/pve/vm-107-disk-0
  LV Size 10.00 GiB

2. Check the file system inside the disk and compose the information in it

e2fsck -fy /dev/pve/vm-107-disk-0

e2fsck 1.46.5 (30-Dec-2021)
Pass 1: Checking inodes, blocks, and sizes
Pass 2: Checking directory structure
Pass 3: Checking directory connectivity
Pass 4: Checking reference counts
Pass 5: Checking group summary information
/dev/pve/vm-107-disk-0: 11575/655360 files (0.1% non-contiguous), 209335/2621440 blocks

3. Shrink the filesystem to the desired size

resize2fs /dev/pve/vm-107-disk-0 5G

resize2fs 1.46.5 (30-Dec-2021)
Resizing the filesystem on /dev/pve/vm-107-disk-0 to 1310720 (4k) blocks.
The filesystem on /dev/pve/vm-107-disk-0 is now 1310720 (4k) blocks long.

4. Reducing the logical volume size

lvreduce -L 5G /dev/pve/vm-107-disk-0

  WARNING: Reducing active and open logical volume to 5.00 GiB.
  THIS MAY DESTROY YOUR DATA (filesystem etc.)
Do you really want to reduce pve/vm-107-disk-0? [y/n]: y
  Size of logical volume pve/vm-107-disk-0 changed from 10.00 GiB (2560 extents) to 5.00 GiB (1280 extents).
  Logical volume pve/vm-107-disk-0 successfully resized.

5. If you have lvm-thin, you can reduce the size of the volume after that

mkdir temp
mount /dev/pve/vm-107-disk-0 temp
fstrim -v temp
resize2fs /dev/pve/vm-107-disk-0
umount temp
rm -r temp

6. Update disk information in Proxmox

nano /etc/pve/lxc/107.conf

Where we replace rootfs: local-lvm:vm-107-disk-0,size=10G with rootfs: local-lvm:vm-107-disk-0,size=5G.

Done! The disk size has now been reduced to 5Gb!