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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.
## Contents
* [1 Method](#Method)
* [2 Process](#Process)
* [2.1 Boot and setup](#Boot_and_setup)
* [2.2 Resize filesystem](#Resize_filesystem)
* [2.3 Resize LVM logical volume](#Resize_LVM_logical_volume)
* [2.4 Resize LVM physical Volume](#Resize_LVM_physical_Volume)
* [2.5 Resize LUKS volume](#Resize_LUKS_volume)
* [2.6 Resize the partition](#Resize_the_partition)
* [2.7 Create a new partition](#Create_a_new_partition)
* [2.8 Recover the logical volume buffer](#Recover_the_logical_volume_buffer)
* [3 Enlarge LVM on LUKS](#Enlarge_LVM_on_LUKS)
* [3.1 Preparation](#Preparation)
* [3.2 Extending the physical segments of the cryptdevice](#Extending_the_physical_segments_of_the_cryptdevice)
* [3.3 Resizing the logical volume](#Resizing_the_logical_volume)
* [3.4 Resizing the encrypted volume](#Resizing_the_encrypted_volume)
## Method
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 `ext4`.
The entire process should run from a live USB Arch system to avoid any filesystem corruption.
## Process
**Warning:** **Do not** run any of this code by copy-pasting, you need to adapt all these commands to your specific setup.
**Note:** It is highly recommended to write out the exact transition plan so that at each step you know exactly which partition size you're going to need.
### Boot and setup
Boot into your live [USB flash installation media](/index.php/USB_flash_installation_media "USB flash installation media").
Decrypt the LUKS volume:
```
# cryptsetup luksOpen /dev/sda2 cryptdisk
```
### Resize filesystem
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/vgroup/lvhome 70g
```
**Note:** `resize2fs` works only on ext{2,3,4} filesystems.
You can run a `fsck` just to make sure nothing broke:
```
# e2fsck -f /dev/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
```
**Note:** To calculate how many sectors we want to shrink to, use a simple formula: `NEW_SECTORS = EXISTING_SECTORS * NEW_SIZE_IN_GB / EXISTING_SIZE_IN_GB`. Remember to take a safety buffer here as well.
Resize the LUKS volume:
```
# cryptsetup -b $NEW_SECTOR_COUNT resize cryptdisk
```
### Resize the partition
Use parted to actually resize the partition:
```
# parted /dev/sda
```
Select `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.
## Enlarge LVM on LUKS
Enlarging a LVM-on-LUKS logical partition, for instance after migrating to a larger hard disk, is done in the opposite way - from the outermost to the innermost partition:
`primary partition(LUKS device{volume group[(logical partition1)(logical partition2-->)]})`
### Preparation
Create a new partition on the new hard disk of wanted size, f.i. by using [GNU Parted](/index.php/GNU_Parted "GNU Parted"), and clone the old partition `sdX1`, containing your LUKS container, into the new partition `sdY1`:
```
# dd if=/dev/sdX1 of=/dev/sdY1 bs=4M
```
### Extending the physical segments of the cryptdevice
Now, open the cryptdevice `CryptDisk` on the new hard disk:
```
# cryptsetup open /dev/sdY1 CryptDisk
```
Take a look at your current physical volume. In this example, we have a cryptdevice `CryptDisk` containing a volume group `CryptVolumeGroup` of two partitions `root` and `home`:
```
# pvdisplay -m
--- Physical volume ---
PV Name /dev/mapper/CryptDisk
VG Name CryptVolumeGroup
PV Size <118.75 GiB / not usable 3.00 MiB
Allocatable yes (but full)
PE Size 4.00 MiB
Total PE 30399
Free PE 0
Allocated PE 30399
PV UUID hu0iA9-i8fv-2SC1-C6ys-LQCz-sptQ-RSOUE5
--- Physical Segments ---
Physical extent 0 to 6399:
Logical volume /dev/CryptVolumeGroup/root
Logical extents 0 to 6399
Physical extent 6400 to 30398:
Logical volume /dev/CryptVolumeGroup/home
Logical extents 0 to 23998
```
By taking the total physical extents (PE) times the PE's size, we get the total size of the physical volume (PV), in this case 118.75 GiB. Although pvdisplay does not show the free extents, we can enlarge the PV to use all the available remaining space of the partition:
```
# pvresize /dev/mapper/CryptDisk
```
Now we get:
```
# pvdisplay -m
...
--- Physical Segments ---
Physical extent 0 to 6399:
Logical volume /dev/CryptVolumeGroup/root
Logical extents 0 to 6399
Physical extent 6400 to 30398:
Logical volume /dev/CryptVolumeGroup/home
Logical extents 0 to 23998
Physical extent 30399 to 60922:
FREE
```
Note the free extents at the end of the PV. Calculate the size difference by taking the free physical extends times PE size - in that case (60922-30399)*4 MiB = 119.2 GiB.
### Resizing the logical volume
Now we are going to resize the second logical volume (LV), in this case containing the /home partition, by the size of the free physical extents minus some safety space:
```
# lvresize -L +119G
```
Note the new size of the second logical volume. Calculate its total size by taking the total logical extends time the PE size - in that case 53438 * 4 MiB = 208.7 GiB:
```
# pvdisplay -m
...
--- Physical Segments ---
Physical extent 0 to 6399:
Logical volume /dev/CryptVolumeGroup/root
Logical extents 0 to 6399
Physical extent 6400 to 59838:
Logical volume /dev/CryptVolumeGroup/home
Logical extents 0 to 53438
Physical extent 59839 to 60922:
FREE
```
### Resizing the encrypted volume
Now we are going to resize the encrypted volume itself. By taking in account the total size of the logical volume minus some safety space:
```
# resize2fs -p /dev/CryptVolumeGroup/Home 208G
```
Execute e2fsck, if asked. That's it.