This article follows the process of resizing and shrinking an LVM-on-LUKS-on-GPT partition, such that an extra (plain) partition can be added in the unused space cleared up on the end of the hard drive.
We do all the resizes from the innermost partition to the outermost on, keeping 1G buffers along the way on each step. It is possible to keep smaller buffers, but that should be done carefully, especially where there are manual calculations.
The filesystem we work on will have the following strucure:
# lsblk NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT sda 8:0 0 111.8G 0 disk ├─sda1 8:1 0 99M 0 part /boot └─sda2 8:2 0 111.7G 0 part └─vgroup 254:0 0 111.7G 0 crypt ├─vgroup-lvroot 254:1 0 30G 0 lvm / └─vgroup-lvhome 254:2 0 81.7G 0 lvm /home
The goal is to clear up unused space and create a new partition,
sda3, without any data loss. All filesystems are assumed to be
The entire process should run from a live USB Arch system to avoid any filesystem corruption.
Boot and setup
Boot into your live USB flash installation media.
Decrypt the LUKS volume:
# cryptsetup luksOpen /dev/sda2 cryptdisk
First we need to resize the innermost filesystem itself. In this case, we only resize the last and largest filesystem and shave off 11GB:
# resize2fs -p /dev/mapper/vgroup-lvhome 70g
You can run a
fsck just to make sure nothing broke:
# e2fsck -f /dev/mapper/vgroup-lvhome
Resize LVM logical volume
We now resize the logical volume, keeping a safety buffer from the filesystem (reduce only by 10GB, not 11GB):
# lvreduce -L -10G /dev/vgroup/lvhome
Resize LVM physical Volume
Again we keep a large safety buffer:
# pvresize --setphysicalvolumesize 102G /dev/mapper/cryptdisk
Resize LUKS volume
First, we need to calculate how many sectors we'll be shaving off by comparing to the existing number of sectors:
# cryptsetup status cryptdisk
Resize the LUKS volume:
# cryptsetup -b $NEW_SECTOR_COUNT resize cryptdisk
Resize the partition
Use parted to actually resize the partition:
# parted /dev/sda
resizepart 2 and give the partition a new size based on your calculations.
Create a new partition
This is a GPT disk so run:
# gdisk /dev/sda
and add the new partition on the remaining free space. If all went well there should be no data loss.
Recover the logical volume buffer
At the end of this process, the filesystem of your
lvhome volume will be 1GB smaller than the underlying logical volume.
In order to regain this 1GB, first verify that the filesystem is clean:
# e2fsck -f /dev/vgroup/lvhome
Then resize the filesystem to occupy the whole logical volume:
# resize2fs /dev/vgroup/lvhome
If all went fine, your
lvhome filesystem is now as large as your logical volume itself.