Resizing LVM PVs (physical volumes — see this diagram)

resizing root partition

1. Boot into a LiveCD that has LVM support built-in.
   • Ubutnu Live
     • after booting, do apt-get update; apt-get install lvm2
   • for SLAX, include this module
2. Locate and activate the LVMs.
   • vgscan --mknodes
   • vgchange -ay
   • lvscan

shrinking

1. "Defragment" the PEs (physical extents)
   • pvmove -v --alloc anywhere /dev/sda5
   • The man page says "pvresize will refuse to shrink PhysicalVolume if it has allocated extents after where its new end would be. In the future, it should relocate these elsewhere in the volume group if there is sufficient free space, like pvmove does."
     • Ignore this — the 'pvmove --alloc anywhere' thing does work
2. Shrink the PV
   • lvm pvresize --setphysicalvolumesize 40G /dev/sda1
3. Shrink the physical partition.
   delete and recreate with fdisk (using gparted won't work -- gparted wants to be able to resize the filesystem too, which it's unable to do)

expanding

1. expand the physical partition (eg. in gparted)
2. lvm pvresize /dev/sda1
   • it will automatically take up the entire partition

calculating the correct partition size after shrinking

1. lvm pvs --units s
2. ... SEE HERE

External links

• http://muzso.hu/2009/07/28/how-to-resize-an-lvm-physical-volume-without-a-reboot
• http://www.redhat.com/archives/linux-lvm/2004-December/msg00049.html
• http://fedoraunity.org/Members/zcat/shrink-lvm-for-new-partition
• http://www.linuxquestions.org/questions/linux-general-1/how-do-i-shrink-a-volume-group-once-i-have-created-free-space-in-it-765047/#post3735891