How to resize LVM logical volumes with ext4 as filesystem

Ever been in the situation where you needed to save some important files to a server and your greeted with “Not enough space left on device”-kind messages? No? Well, as that happened too often too me for my liking, I decided to do it right this time when I set up my home server and use logical volume manager (LVM) straight from the start. So basically, all I had to do was to shrink a filesystem that had free space in it and its partition (logical volume (LV) to be precisely) afterwards and then to resize the logical volume/filesystem where I needed the space.

As all the necessary tools are available normally on a system with LVM support, I could dive right in:

# Unmount the filesystem and check its' LV
umount /mnt/foo
e2fsck -f /dev/mapper/vg0-foo

# Shrink ext4 and then the LV to the desired size
resize2fs -p /dev/mapper/vg0-foo 40G
lvreduce -L 40G /dev/mapper/vg0-foo

# Before continuing, run e2fsck. If it bails because the partition
# is too small, don't panic! The LV can still be extended with
# lvextend until e2fsck succeeds, e.g.: 
# lvextend -L +1G /dev/mapper/vg0-foo
e2fsck -f /dev/mapper/vg0-foo

# Resize the filesystem to match the LVs size, check and mount it
resize2fs -p /dev/mapper/vg0-foo
e2fsck -f /dev/mapper/vg0-foo
mount /mnt/foo

That was the tricky part. The rest is pretty straight forward:

  • unmount the filesystem,
  • extend the logical volume and
  • expand the filesystem afterwards.
umount /mnt/bar

# Extend the LV to use all free space
lvextend -l +100%FREE /dev/mapper/vg0-bar
e2fsck -f /dev/mapper/vg0-bar

# Resize the partition to fill the LV
resize2fs -p /dev/mapper/vg0-bar
e2fsck -f /dev/mapper/vg0-bar
mount /mnt/bar

References

2010
09/16
CATEGORY
Data Management
ext4
Linux
LVM
Ubuntu
Ubuntu Server
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  1. This guide was really simple and really helpful. I used it to enlarge my / partition using the Ubuntu Rescue Mode. Thanks for the help!

  2. Thxs buddy…
    Try this link, very easy to understand

    http://www.redhatlinux.info/2010/11/lvm-logical-volume-manager.html

  3. Many thanks for this tips !!!

  4. Handy reference to do the exact thing I’m doing now.
    Thanks.

    • mp
    • July 19th, 2011

    Steps 16/17 aren’t necessary if line 13 is successful no? Thx

    • Well that depends. If you _don’t_ want your partition to fill the LV completely, then yes, they are not necessary.

        • Steve Nordquist
        • August 31st, 2011

        That’s peculiar to LVM somehow measuring the closest size differently from ext4, actually; and it doesn’t explain all the fscking when ext4 can be resized live (subject to programs and scripts that freak right out at something as pedestrian now as volume/partition/lvm/filesystem/cloud changes. Are you hardness testing versus filesystem fuzzing?) I don’t even get a certificate of having defragged twice for all that wear ‘n tear down.

        Part 2’s lines 5 and 9 (fsck, as if lvm cared or resize2fs was inadequate,) are pure garbage (better than tainted garbage, but meh.)

    • mike
    • October 18th, 2011

    Steve Nordquist :
    …
    Part 2′s lines 5 and 9 (fsck, as if lvm cared or resize2fs was inadequate,) are pure garbage (better than tainted garbage, but meh.)

    Steve,

    resize2fs (at least in some environments) forces you to do a fsck -f beforehand. The one after isn’t absolutely necessary, but as it’s EXT4 it’s a quick procedure and certainly isn’t going to hurt anything.

    • Dan
    • May 28th, 2013

    Thank you so much. Super painless.

  8. I think there is a small typo in your second command snippet:

    Should not this line

    # Extend the LV to use all free space
    lvextend -l +100%FREE /dev/mapper/vg0-bar

    be instead like this?

    lvextend -L +100%FREE /dev/mapper/vg0-bar

    • No, -l is just fine because I want the LV to use the remaining space and that is only possible with that parameter. From the man page: {-l|--extents
      [+]LogicalExtentsNumber[%{VG|LV|PVS|FREE|ORIGIN}] | -L|--size
      [+]LogicalVolumeSize[bBsSkKmMgGtTpPeE]}

    • NStorm
    • June 5th, 2014

    Why not just use lvreduce/lvextend with -r key, which auto-resizes fs to match new LV size?

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