shrink_lv

shrink_lv

The shrink_lv role is used to decrease the size of logical volumes and the file system within them.

The role is designed to support the automation of RHEL in-place upgrades, but can also be used for other purposes.

Contents

The role contains the shell scripts to shrink the logical volume and file system, as well as the script wrapping it to run as part of the pre-mount step during the boot process.

Role Variables

shrink_lv_devices

The variable shrink_lv_devices is the list of logical volumes to shrink and the target size for those volumes.

device

The device that is mounted as listed under /proc/mount. If the same device has multiple paths, e.g. /dev/vg/lv and /dev/mapper/vg/lv pass the path that is mounted

size

The target size of the logical volume and filesystem after the role has completed. The value can be either in bytes or with optional single letter suffix (1024 bases). See Unit options type iec of numfmt

Example of a playbook to run the role

The following yaml is an example of a playbook that runs the role against all hosts to shrink the logical volume lv in volume group vg to 4G.

- name: Shrink Logical Volumes playbook
  hosts: all
  vars:
    shrink_lv_devices:
      - device: /dev/vg/lv
        size: 4G
  roles:
    - shrink_lv

Validate execution

The script will add an entry to the kernel messages (/dev/kmsg or /var/log/messages) with success or failure. In case of failure, it may also include an error message retrieved from the execution of the script.

A successful execution will look similar to this:

[root@localhost ~]# cat /var/log/messages |grep Resizing -A 2 -B 2
Oct 16 17:55:00 localhost /dev/mapper/rhel-root: 29715/2686976 files (0.2% non-contiguous), 534773/10743808 blocks
Oct 16 17:55:00 localhost dracut-pre-mount: resize2fs 1.42.9 (28-Dec-2013)
Oct 16 17:55:00 localhost journal: Resizing the filesystem on /dev/mapper/rhel-root to 9699328 (4k) blocks.#012The filesystem on /dev/mapper/rhel-root is now 9699328 blocks long.
Oct 16 17:55:00 localhost journal:  Size of logical volume rhel/root changed from 40.98 GiB (10492 extents) to 37.00 GiB (9472 extents).
Oct 16 17:55:00 localhost journal:  Logical volume rhel/root successfully resized.