Hi all - this is really a linux ... 'WTF? question, but I am not really signed up for any linux-specific answer sources, and there are some knowledgable people here ...

I am seeing this after my home server had a hiccup, when attempting to mount the (ext4) partition of a 1.5TB SATA drive

jkn@obrien:~$ sudo mkdir /mnt/newbackup
jkn@obrien:~$ sudo mount /dev/sde1 /mnt/newbackup
jkn@obrien:~$ ls -l /mnt/newbackup
# (many files listed)
jkn@obrien:~$ sudo umount /mnt/newbackup

OK, so far so good. Now try with a dirrerent mount point:

jkn@obrien:~$ sudo mkdir /mnt/backup
jkn@obrien:~$ sudo mount /dev/sde1 /mnt/backup
jkn@obrien:~$ ls /mnt/backup
jkn@obrien:~$ # (ie. no files listed)

WTF?!

There appears to be no difference between the (just-created) mount points.

jkn@obrien:~$ ls -l /mnt
total 244
drwxr-xr-x 2 root root 4096 May 17 18:17 backup
drwxr-xr-x 2 root root 4096 May 17 18:16 newbackup

even though the second mount returns with $?=0, it actually seems to fail; lsblk doesn't show it as mounted.

dmesg has the same entry for both attempts:
[36291.436752] EXT4-fs (sde1): mounted filesystem with ordered data mode. Opts: (null)
[36355.625768] EXT4-fs (sde1): mounted filesystem with ordered data mode. Opts: (null)

This actually started when I had problems with '/mnt/backup'. At one time I had this as immutable, (chattr +i), and the drive was autofs mounted on my remote desktop. But in this little demo I am creating both mount points from ...

Any clue where I might look further to try and understand what is going on?

Thanks a lot, Jon N

jkn <jkn_gg@nicorp.f9.co.uk> writes:

> Hi all - this is really a linux ... 'WTF? question, but I am not
> really signed up for any linux-specific answer sources, and there are
> some knowledgable people here ...
>
> I am seeing this after my home server had a hiccup, when attempting to
> mount the (ext4) partition of a 1.5TB SATA drive
>
> jkn@obrien:~$ sudo mkdir /mnt/newbackup
> jkn@obrien:~$ sudo mount /dev/sde1 /mnt/newbackup
> jkn@obrien:~$ ls -l /mnt/newbackup
> # (many files listed)
> jkn@obrien:~$ sudo umount /mnt/newbackup
>
> OK, so far so good. Now try with a dirrerent mount point:
>
> jkn@obrien:~$ sudo mkdir /mnt/backup
> jkn@obrien:~$ sudo mount /dev/sde1 /mnt/backup
> jkn@obrien:~$ ls /mnt/backup
> jkn@obrien:~$ # (ie. no files listed)
>
> WTF?!
>
> There appears to be no difference between the (just-created) mount points.
>
> jkn@obrien:~$ ls -l /mnt
> total 244
> drwxr-xr-x 2 root root 4096 May 17 18:17 backup
> drwxr-xr-x 2 root root 4096 May 17 18:16 newbackup
>
> even though the second mount returns with $?=0, it actually seems to
> fail; lsblk doesn't show it as mounted.
>
> dmesg has the same entry for both attempts:
> [36291.436752] EXT4-fs (sde1): mounted filesystem with ordered data
> mode. Opts: (null)
> [36355.625768] EXT4-fs (sde1): mounted filesystem with ordered data
> mode. Opts: (null)
>
> This actually started when I had problems with '/mnt/backup'. At one
> time I had this as immutable, (chattr +i), and the drive was autofs
> mounted on my remote desktop. But in this little demo I am creating
> both mount points from ...
>
> Any clue where I might look further to try and understand what is going on?

Most likely you are experiencing the behavior described here:

https://unix.stackexchange.com/questions/169909/systemd-keeps-unmounting-a-removable-drive

--
https://www.greenend.org.uk/rjk/

On Monday, May 17, 2021 at 8:32:21 PM UTC+1, Richard Kettlewell wrote:
> jkn <jkn...@nicorp.f9.co.uk> writes:
>
> > Hi all - this is really a linux ... 'WTF? question, but I am not
> > really signed up for any linux-specific answer sources, and there are
> > some knowledgable people here ...
> >
> > I am seeing this after my home server had a hiccup, when attempting to
> > mount the (ext4) partition of a 1.5TB SATA drive
> >
> > jkn@obrien:~$ sudo mkdir /mnt/newbackup
> > jkn@obrien:~$ sudo mount /dev/sde1 /mnt/newbackup
> > jkn@obrien:~$ ls -l /mnt/newbackup
> > # (many files listed)
> > jkn@obrien:~$ sudo umount /mnt/newbackup
> >
> > OK, so far so good. Now try with a dirrerent mount point:
> >
> > jkn@obrien:~$ sudo mkdir /mnt/backup
> > jkn@obrien:~$ sudo mount /dev/sde1 /mnt/backup
> > jkn@obrien:~$ ls /mnt/backup
> > jkn@obrien:~$ # (ie. no files listed)
> >
> > WTF?!
> >
> > There appears to be no difference between the (just-created) mount points.
> >
> > jkn@obrien:~$ ls -l /mnt
> > total 244
> > drwxr-xr-x 2 root root 4096 May 17 18:17 backup
> > drwxr-xr-x 2 root root 4096 May 17 18:16 newbackup
> >
> > even though the second mount returns with $?=0, it actually seems to
> > fail; lsblk doesn't show it as mounted.
> >
> > dmesg has the same entry for both attempts:
> > [36291.436752] EXT4-fs (sde1): mounted filesystem with ordered data
> > mode. Opts: (null)
> > [36355.625768] EXT4-fs (sde1): mounted filesystem with ordered data
> > mode. Opts: (null)
> >
> > This actually started when I had problems with '/mnt/backup'. At one
> > time I had this as immutable, (chattr +i), and the drive was autofs
> > mounted on my remote desktop. But in this little demo I am creating
> > both mount points from ...
> >
> > Any clue where I might look further to try and understand what is going on?

Hi Richard

> Most likely you are experiencing the behavior described here:
>
> https://unix.stackexchange.com/questions/169909/systemd-keeps-unmounting-a-removable-drive
>
Ah yes, systemd, of course! Thanks a lot.

Yes, looks like it is that - I suppose the fact that I had the 'original' entry in /etc/fstab might have given me
a clue...

Actually, I am pretty sure I tried 'systemctl daemon-reload' earlier on when trying to track down the issue ...
but I can't remember now what I observed at the time!

Anyway, I can see from 'journalctl' that systemd is indeed implicated, I think I can take it from here.

Thanks a lot, Jon N