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1. Using LVM

For partitions created on Logical Volume Manager (LVM) (Linux feature) at install time, they can be resized easily by concatenating extents onto them or truncating extents from them over multiple storage devices without major system reconfiguration.

Caution: Deployment of the current LVM system may degrade guarantee against filesystem corruption offered by journaled filesystems such as ext3fs unless their system performance is sacrificed by disabling write cache of hard disk.

Run a df from terminal.

$ df
Filesystem	1K-blocks	Used	Available	Use%	Mounted on
/dev/mapper/VolGroup00-LogVol00	7935392	6773500	752292	91%	/
/dev/sda5	497829	20904	451223	5%	/boot
tmpfs	1037084	0	1037084	0%	/dev/shm
/dev/mapper/VolGroup00-LogVol01	70877776	14988144	51045372	23%	/home

We have two partitions here, / partition is about 8 Gb and the /home partition is about 71 Gb. What we are trying to do is to expand the / partition to 10 Gb by taking free space from /home.

For /home you do:

# sudo umount /home
# sudo e2fsck -f /dev/VolGroup00/LogVol01
# resize2fs /dev/VolGroup00/LogVol01 69G
# lvreduce -L-2G /dev/VolGroup00/LogVol01
# mount /home

For / you do:

# lvextend -L+2G /dev/VolGroup00/LogVol00
# resize2fs /dev/VolGroup00/LogVol00

e2fsck and resize2fs belong to package e2fsprogs.

After resizing you will get

$ df
Filesystem	1K-blocks	Used	Available	Use%	Mounted on
/dev/mapper/VolGroup00-LogVol00	9299624	6779304	2043564	77%	/
/dev/sda5	497829	20904	451223	5%	/boot
tmpfs	1037084	0	1037084	0%	/dev/shm
/dev/mapper/VolGroup00-LogVol01	68877776	14999888	51033628	23%	/home

Read the lvm-howto for detailed infotmation.

2. Mounting another partition

If you have an empty partition (e.g., “/dev/sdx”), you can format it with mkfs.ext3(1) and mount(8) it to a directory where you need more space. (You need to copy original data contents.)

$ sudo mv work-dir old-dir
$ sudo mkfs.ext3 /dev/sdx
$ sudo mount -t ext3 /dev/sdx work-dir
$ sudo cp -a old-dir/* work-dir
$ sudo rm -rf old-dir

3. Using symlink

This might be the easiest way. If you have an empty directory (e.g., “/path/to/emp-dir”) in another partition with usable space, you can create a symlink to the directory with ln(8).

$ sudo mv work-dir old-dir
$ sudo mkdir -p /path/to/emp-dir
$ sudo ln -sf /path/to/emp-dir work-dir
$ sudo cp -a old-dir/* work-dir
$ sudo rm -rf old-dir

4. Using aufs

If you have usable space in another partition (e.g., “/path/to/”), you can create a directory in it and stack that on to a directory where you need space with aufs. With aufs you can unite several directories into a single virtual filesystem.

$ sudo mv work-dir old-dir
$ sudo mkdir work-dir
$ sudo mkdir -p /path/to/emp-dir
$ sudo mount -t aufs -o br:/path/to/emp-dir:old-dir none work-dir