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carl avatar Ubuntu

why cannot umount an lvm partition?

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carl

I have an Ubuntu Server 22.04. The disks are managed using LVM partition. My /var partition needs a size increasing. So I thought to reduce the /home size, so that I could increase /var.

root@localhost:/mnt# lsblk
NAME        MAJ:MIN RM   SIZE RO TYPE MOUNTPOINTS
loop0         7:0    0  53.3M  1 loop /snap/snapd/19457
loop1         7:1    0 111.9M  1 loop /snap/lxd/24322
loop2         7:2    0  63.4M  1 loop /snap/core20/1974
sda           8:0    0 465.8G  0 disk
sdb           8:16   1     0B  0 disk
sdc           8:32   1     0B  0 disk
sdd           8:48   1     0B  0 disk
sde           8:64   1     0B  0 disk
sdf           8:80   0  74.5G  0 disk
├─sdf1        8:81   0     1M  0 part
├─sdf2        8:82   0     1G  0 part /boot
└─sdf3        8:83   0  73.5G  0 part
  ├─vg-root 253:0    0    50G  0 lvm  /
  ├─vg-var  253:1    0   7.8G  0 lvm  /var
  ├─vg-usr  253:2    0    60G  0 lvm  /usr
  ├─vg-tmp  253:3    0     8G  0 lvm  /tmp
  └─vg-home 253:4    0 413.5G  0 lvm
sdg           8:96   0 465.8G  0 disk
├─vg-root   253:0    0    50G  0 lvm  /
├─vg-var    253:1    0   7.8G  0 lvm  /var
├─vg-usr    253:2    0    60G  0 lvm  /usr
└─vg-home   253:4    0 413.5G  0 lvm

root@localhost:/mnt# df -h
Filesystem                                                                                    Size  Used Avail Use% Mounted on
tmpfs                                                                                         794M  1.4M  793M   1% /run
/dev/mapper/vg-root                                                                            50G  4.1G   43G   9% /
/dev/disk/by-id/dm-uuid-LVM-Den324vgGMdBQrsjrKyrasUtU1NAEV5lNap1uxEhuN2eMmWivFx921LEtPAxYSDd   59G  3.7G   53G   7% /usr
tmpfs                                                                                         3.9G  4.0K  3.9G   1% /dev/shm
tmpfs                                                                                         5.0M     0  5.0M   0% /run/lock
/dev/mapper/vg-home                                                                           407G  118G  273G  31% /home
/dev/sdf2                                                                                     974M  131M  777M  15% /boot
/dev/mapper/vg-tmp                                                                            7.8G  120K  7.4G   1% /tmp
/dev/mapper/vg-var                                                                            7.6G  6.0G  1.3G  83% /var
tmpfs                                                                                         794M  4.0K  794M   1% /run/user/1000

The first problem I faced was to umount /home. Even if I am logged as root and I am under mnt directory. So I resolved that by root@localhost:/mnt# umount -f /home , thereafter checking lsof /home and no processes were found.

After that I wanted to check the file -system error using e2fsck -fy /dev/mapper/vg-home and surprisingly I got:

root@localhost:/mnt# e2fsck -fy /dev/mapper/vg-home
e2fsck 1.46.5 (30-Dec-2021)
/dev/mapper/vg-home is in use.
e2fsck: Cannot continue, aborting.

I ran lsof /dev/mapper/vg-home and no processes were running. I don't understand why /dev/mapper/vg-home is in use even if /home is umount?

Any suggestion, idea or help is very appreciated.

EDIT:

 # lvscan

 ACTIVE            '/dev/vg/root' [50.00 GiB] inherit
 ACTIVE            '/dev/vg/var' [<7.76 GiB] inherit
 ACTIVE            '/dev/vg/usr' [60.00 GiB] inherit
 ACTIVE            '/dev/vg/tmp' [8.00 GiB] inherit
 ACTIVE            '/dev/vg/home' [413.52 GiB] inherit
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lvm
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steeldriver
What does `lvscan` say about the volume(s)?
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carl avatar
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carl
@steeldriver - you can now see what ```lvscan``` said. I have mounted the ```/home```.
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waltinator avatar
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waltinator
You can't unmount an in-use partition. `/var` is heavily used. Rather, boot from a live USB stick (your install medium, in "Try Ubuntu" mode.
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carl avatar
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carl
@waltinator - my problem is ```/home``` and ```/dev/vg/home``` to ```umount``` and reduce the size so that I can increase the ```/var``` size. I don't need to ```umount``` ```/var``` to increase the size.
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waltinator avatar
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waltinator
You could use `lsof` with the `+D directory` option, or `fuser` to see all the processes with files open on that directory and subdirectories, that you would need to kill before you unmount. Don't do that. Rather, boot from a live USB stick (your install medium, in "Try Ubuntu" mode
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