I have a somewhat bizzare problem at the moment with my Debian-system (mainly testing).

I used to have a root-partition on lvm that was formatted as ext3.

I now booted a live-system and converted the ext3 into ext4 (via tune2fs...) and also did a fsck.ext4. In the live-system I can mount the partition as ext4.

Then I changed the entry in /etc/fstab from ext3 to ext4 and rebooted my Debian.

The problem is that the partition (even though it says ext4 in /etc/fstab) seems still be to mounted as ext3 - at least that is what mount says.

When I try to determine the filesystem-type I get inconsistent results:

fsck -N reports ext4:

sudo fsck -N /dev/mapper/hed-root 
fsck from util-linux 2.20.1
[/sbin/fsck.ext4 (1) -- /] fsck.ext4 /dev/mapper/hed-root 

but blkid says ext3

sudo blkid -o value -s TYPE /dev/mapper/hed-root 

As I said the filesystem resides in a lvm-volume. I changed nothing there.

What can I do to resolve this?

Many thanks!

  • "at least that is what mount says" – :-) The truth is hidden in cat /proc/mounts. Can you mount other volumes as ext4? How old is the kernel? Does the initrd maybe need explicit ext4 support? May 7, 2013 at 0:51
  • In /proc/mounts: /dev/mapper/hed-root / ext3 rw,relatime,errors=remount-ro,user_xattr,barrier=1,data=ordered 0 0
    – morgon
    May 7, 2013 at 1:00
  • Kernel is 3.2.0
    – morgon
    May 7, 2013 at 1:01
  • What is the output of dumpe2fs -h /dev/mapper/hed-root | grep "^Filesystem features:"? I guess your tune2fs operation has failed (what exactly did you do with it?) because in case of success the volume would be supposed to not be mountable any more as ext3 at all. May 7, 2013 at 1:13
  • Yeah agree with Hauke, as ext4 is not back ported after successful conversion and would never be able to mount as ext3, looks like something went wrong. May 7, 2013 at 1:20

2 Answers 2


blkid might still be using old cache entry for that LV.

You can make sure that blkid is reporting correct information by bypassing cache:

sudo blkid -p /dev/mapper/hed-root

Also can do a garbage collection pass on cache:

sudo blkid -g /dev/mapper/hed-root

Hope this helps.

  • blkid -p (after garbage collection) reports "/dev/mapper/hed-root: UUID="9a8d1cc1-3dba-4fc7-9329-45fba5ff3f7e" VERSION="1.0" TYPE="ext3" USAGE="filesystem" "
    – morgon
    May 7, 2013 at 1:03
  • Oh i did not see this one: In /proc/mounts: /dev/mapper/hed-root / ext3 rw,relatime,errors=remount-ro,user_xattr,barrier=1,data=ordered 0 0 . Can you do "mount -o rw,remount,defaults /dev/mapper/hed-root /"? May 7, 2013 at 1:10
  • I ran the remount, no errors but changes nothing.
    – morgon
    May 7, 2013 at 1:15

Based on your filesystem features output, you didn't actually convert your filesystem to ext4.

To resolve the issue, convert the filesystem to ext4. Reboot your live CD and run the appropriate commands:

tune2fs -O extents,uninit_bg,dir_index /dev/mapper/hed-root
e2fsck -fDC0 /dev/mapper/hed-root

(Note that the ext4 driver is capable of mounting ext2 and ext3 filesystems, which is why your system is currently usable.)

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