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Freeing Disc Space

This page talks about ways to find out how much of the system storage space is used and to free up some of it.

For a description on how to reduce the footprint of a Debian installation see ReduceDebian.

See partitions and discs usage

First of all, to see the existing partitions, use:

sfdisk -l

Then to check which partitions are getting full use:

$ df -lhT

$ df --local --human-readable -T
Filesystem    Type    Size  Used Avail Use% Mounted on
/dev/sda1     ext4    100M  77M  33M  77% /
...

== Full partitions =

If a partition becomes full the system might not work properly.

When your Home directory becomes full, you will not be able to save any file, and some applications might refuse to start correctly.

When your temporary directory (/tmp) becomes full, many applications will fail with error messages such as:

cannot create temp file for document: No space left on device

See which directories are using the most disc space

There are several tools to see which directories are using the most disc space on a Debian system, like baobab in package gnome-utils or the command line program du in the package coreutils that can be used like this:

/usr/bin/du --total --summarize --human-readable --one-file-system

See also ncdu.

Ncdu is a ncurses-based du viewer. It provides a fast and easy to use interface and allows to browse through directories, to show percentages of disk usage and to delete unwanted files.

See which packages are using the most disc space

Command line

To list packages that take up most of the disc space with aptitude into visual mode, select Views → New Flat Package List (this menu entry is available only after etch version), press l and enter ~i, press S and enter ~installsize, then it will give you nice list to work with. Doing this after upgrading aptitude should give you access to this new feature.

In lenny, aptitude has "why" and "why-not".

 aptitude why package1 

shows why package1 may have been installed.

 aptitude why package1 package2 

tries to work out why installing package1 would drag in package2.

"why-not" looks at conflicts.

These commands only provide one possible explanation. Check /var/log/aptitude for definitive information.

Using aptitude to list uninstalled recommended or suggested packages:

aptitude search '~RBsuggests:~i!~i'

To list upgradeable packages:

aptitude search '~U'

To list manually installed packages:

aptitude search '~i!~M'

To install without recommends but not uninstalling other recommends:

aptitude install -R -o Aptitude::Keep-Recommends=true

To list packages in increasing order of size:

aptitude -F '%I %p' search '~i'|egrep '^[0-9]+[\.,]?[0-9]* [MG]B'|sort -n

Remove some cruft

Purge obsolete configuration files:

aptitude purge ~c

Take a look at the Debian Cleanup Tips at http://raphaelhertzog.com/mastering-debian/.

Using dpigs (debian-goodies):

dpigs -n50

Using wajig :

wajig size

Sort installed packages by size:

dpkg-query -W --showformat='${Installed-Size} ${Package}\n' | sort -n

Graphical Interface

synaptic, go to installed packages and click on the size column.

Find things to erase

Categorically Expendable Directories

Temporary

/tmp
/var/tmp

Contents of these directories are only intended to be used in the short term or while a program is running and are generally expendable.

Logs

/var/log

Cache

apt-get clean

or

aptitude clean

Use apt-get autoclean if you want to remove old packages for which you also have the last package.

Spool

Things in

/var/spool

are intended to be processed but may be expendable.

Command line tools to see seldom used files

These function only if file systems are usually mounted with option strictatime.

/usr/bin/find

The following options are of special interest

Duplicate Handling

When you find duplicates, you can hard link them, if they are on the same file system, or remove duplicates to make them unique.

Finders

Files you do not want

=== Packages you do not want ==

Tools to alter files to reduce them

Stripping dbus-daemon exposes a bug in BFD. Executing in find /usr/bin -not -name strip -and -not -name dbus-daemon -execdir strip --strip-unneeded '{}' \;  reduced the size of contents of the directory in a Squeeze installation from 140MB to 120MB.

Do not compress bash or your scripts will crash. Compressed executables may require more memory when run.

Convert spaces to tabs

Can reduce the file size of text files, though the difference is usually slight. For this example you need the commands find of findutils; unexpand of coreutils; and rewrite, which is at http://oss.ezic.com but not packaged.

find -type f -writable -name '*.txt' -exec rewrite '{}' 'unexpand --all' \;

Reduce data creation

Use the following line as your /etc/rsyslog.conf configuration file in order to not save logs but output them on virtual terminal 12:

Output to what would be files can be caused to go to /dev/null in some cases where a symlink does not work as in this example redirecting output from .xsession-errors: mknod .xsession-errors c 1 3

On systems that have been running for some time you might consider removing or compressing old log files. logrotate can assist

File Systems

ReiserFS can pack multiple small files and the ends of larger files into shared blocks, which saves space.

For file systems have blocks and which do not put parts of more than 1 file in a block, such as Ext4FS: using a different block size for the file system may save space depending on the size of the files stored on the file system. A block size of 1KB reduces space useage compared to 4KB for a Debian installation.

The following file systems provide compression.

Application Level / User Space

In Linux

No high confidence of high reliability

These file systems might not be reliable enough to store critical data.

Turn Off Reserved Blocks on ExtFS

By default, ExtFS reserves 5% of the file system for the user 'root' as a safety measure. To turn this off:

tune2fs -r 0 /dev/sda2

This can be done on a mounted filesystem.

Off Line Storage

You may move data to off line storage, such as removable optical discs or discs on an external data bus (such as Firewire or USB).

If you have a read-only source like a write once optical disc, an overlaid unifying file system like aufs or Linux's "union mount" can save changes in a writeable filesystem, saving the user the space of the unchanged portions. The same could be accomplished with a snapshotted filesystem as with Linux Volume Manager (lvm2).

File Compression

The following packages provide programs which losslessly compress data and can operate by a pipe or on files.

External article on parallel compressors

Wish list

See Also


CategorySystemAdministration | CategoryStorage