How to free space and clean up your UCS

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How to free space and clean up your UCS

When using UCS of the course of months or years it can be necessary to free some space from time to time.
This guide will highlight some places and tools that can be used to do that, but please keep in mind:

  1. Always backup before removing things!
  2. Think before you delete something that you still might need!

Analysis

UCS environments differ in what is using space depending on installed services/apps, user/group count, usage, …
Therefore you should never blindly copy & paste the following commands without analyzing your server first.
Every UCS will provide you with du and df to list used and free space. Another great tool to do this is ncdu: You can simply install it via univention-install ncdu and start to analyse with sudo ncdu /.
A normal installation might look like this:

ncdu 1.13 ~ Use the arrow keys to navigate, press ? for help
--- / -------------------------------------------------------------------------------------
    9,6 GiB [##########] /var
    8,3 GiB [########  ] /usr
  370,5 MiB [          ] /lib
   74,7 MiB [          ] /boot
   64,1 MiB [          ] /home
   46,0 MiB [          ] /opt
   38,4 MiB [          ] /root
   32,1 MiB [          ] /etc
   13,7 MiB [          ] /sbin
   11,3 MiB [          ] /bin
    1,5 MiB [          ] /run
   88,0 KiB [          ] /tmp
   16,0 KiB [          ] /dev
e  16,0 KiB [          ] /lost+found
    8,0 KiB [          ] /media
    4,0 KiB [          ] /lib64
e   4,0 KiB [          ] /srv
e   4,0 KiB [          ] /mnt
.   0,0   B [          ] /proc
    0,0   B [          ] /sys
@   0,0   B [          ]  initrd.img
@   0,0   B [          ]  initrd.img.install
@   0,0   B [          ]  vmlinuz
@   0,0   B [          ]  vmlinuz.install

 Total disk usage:  18,6 GiB  Apparent size:  18,6 GiB  Items: 605601

It is possible to navigate directories via the arrow keys so that you can look further into your disk usage.

Guides

There are several guides for clean up and freeing space available here:

Standard UCS

In bigger environments the MDB maxsize can be reached sooner or later for the LDAP, Listener cache or Translog as space is not freed after deletion of objects.
To do so the following guides have useful information - It is necessary to execute the optional steps too (e.g. creating new database files via mdb_copy). A comparison of both the old and the new MDB file should report the size difference after this “defragmentation”.

UCS@school

Useful commands

Last but not least there are several other things that might pollute your UCS but can be cleaned easily:

Clean unused packages and apt cache

apt autoremove
apt-get clean
univention-prune-kernels

Clean up the group membership cache

/usr/share/univention-group-membership-cache/univention-ldap-cache cleanup

Delete old systemd logs

sudo journalctl --vacuum-time=2d

Remove unused docker resources

docker system prune

UCS internals

UCS keeps several logs in rotation. If some services emitted many logging state, for example after importing many users, the log is kept for some time, so it is advisable to check /var/log/univention for some bigger gzipped logs.

UCS keeps daily backups of LDAP and UCR: 3.3. LDAP directory — Univention Corporate Server - Manual for users and administrators
These can be moved away to free space too.

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