---
title: Resize partitions on an encrypted disc
date: 2015-03-20
tags: [code, linux]
description: The Debian installer chose to use only 10GB for the root partition. So now I was tasked with resizing the partitions.
---

Recently I installed a fresh debian jessie on my laptop.  I used this
opportunity not just to switch to the next debian version, I also switched to
64 bit and encrypted my disc.  I had no experience with encrypted disc setups
so I trusted the debian installer.  It offered several default partition
options of which I chose to have a root partition with a separate home
partition.

The trouble is now that the installer chose to use only 10GB for the root
partition which I used up in the first week. So now I was tasked with resizing
the partitions.

## What I already knew

In the past I had used [gparted](http://gparted.org/) for task like this one.
Unfortunately, gparted does not support encryptet discs.  I was very
unconfident about doing this without a tool I knew but in the end it turned out
to be rather simple.

If it had not been for the encryption, these are the steps I would have done in
gparted (assuming that `root` takes up the first 10GB of the disc and `home`
uses all the rest):

1.	shrink `home` by 10GB
2.	move `home` to the end of the disc
3.	grow `root`

## the actual situation

The disc layout was roughly like this:

-	there is one physical volume
-	the pysical volume containes a crypt
-	the crypt contains two logical volumns, `root` and `home`
-	the logical volumes both contain an ext\* file system

There were two aspects about this that I did not expect and that significantly
simplify my task:

-	I could completely ignore the encryption part. I only have to think about the
	logical volumes and the filesystems.
-	logical volumes can use available space anywhere on the physical volume. So
	there is no need to "move" `root`.

## what I had to do

-	The necessary operations can not be applied to mounted volumes. So I had to
	boot into a live system.
-	Get access to logical volmes inside of the crypt without mounting them (or
	unmount again)
-	shrink `home`
	-	e2fsck /dev/mapper/localhost--vg-home
	-	resize2fs /dev/mapper/localhost--vg-home 200G
		-	will warn if specified size is smaller than actual data
	-	lvreduce -L -10GB /dev/mapper/localhost--vg-home
	-	resize2fs /dev/mapper/localhost--vg-home
-	grow root
	-	lvextend -L +10GB /dev/mapper/localhost--vg-root
	-	e2fsck /dev/mapper/localhost--vg-root
	-	resize2fs /dev/mapper/localhost--vg-root