Resizing LVM Partitions

Some CERN systems were built with little space in /, with the bulk of the space in /home. However, this means HTCondor, that wants at least 10GB free in the partition where /tmp lives, often cannot run a job. The following procedure takes space out of /home, and puts it into /.

Caveats

• HTCondor was stopped
• The /home partition was umounted for those operations (see cookbook below)

Cookbook

• Do the /home volume size reduction
  • umount /home
  • e2fsck -fy /dev/mapper/vg_pcatum15-lv_home
  • # Size was 405GB, make it 205GB
  • resize2fs /dev/mapper/vg_pcatum15-lv_home 205G
  • # Now reduce the logical volume by the 200GB
  • lvreduce -L -200G /dev/mapper/vg_pcatum15-lv_home
  • # Match everything up for remount consistency
  • resize2fs /dev/mapper/vg_pcatum15-lv_home
  • mount -av

• Now, let's work on the root volume
  • lvdisplay /dev/mapper/vg_pcatum15-lv_root
  • # Grow it by the 200G we just saved
  • lvextend -L +200G /dev/mapper/vg_pcatum15-lv_root
  • # Make sure that 'df' can see this. This is the slowest step
  • resize2fs /dev/mapper/vg_pcatum15-lv_root

References

• http://www.golinuxhub.com/2014/03/how-to-extendresize-lvm-and-volume.html
• https://www.rootusers.com/lvm-resize-how-to-decrease-an-lvm-partition/

-- BobBall - 23 May 2017