Univention Corporate Server (UCS) » Installation

ID #1386

Upgrade to UCS-4.2 blocked due to separate /usr/ file system

UCS-4.2 uses systemd by default, which no longer supports /usr/ being a separate file system. Mounting file systems nowadays requires many helpers, which use libraries and other resources from /usr/ by default. With a separate /usr/ they often break in subtle ways or lead to hard to debug boot problems.

As such the content of /usr/ must be moved to the root file system before the system can be upgraded to UCS-4.2. This procedure should be performed manually and might require resizing the file systems.

  1. Make sure you have a recent backup
  2. Verify that / has enough free space for also containing /usr/:
  3. df -h / /usr
    If not, use
    lvresize -L +XXG /
    followed by
    resize2fs /
    or similar commands to enlarge the root file system size. This works best when you're already using LVM. Otherwise this might require editing the partition table through fdisk or parted, or moving and renaming other partitions, or doing a full backup and restore.
  4. Make sure you have access to the server console for emergency access and login as "root".
  5. Switch the system to "single user mode" by issuing
    telinit 1
  6. Verify that all daemons are stopped:
    ps axf
  7. Move the old file system to /mnt/ by running
    mount --move /usr /mnt
  8. Move the content over to the root file system:
    mv /mnt/* /usr/
  9. Verify that /mnt/ is now empty:
    ls -al /mnt/
  10. Unmount the now empty file system:
    umount /mnt
  11. Update /etc/fstab and remove the line for /usr, so it no longer gets mounted:
    $EDITOR /etc/fstab
  12. Reboot:
    reboot

Tags: /usr, systemd

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Last update: 2017-03-30 10:24
Author: Philipp Hahn
Revision: 1.0

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