Re: mount inconsistencies
On Mon, 12 May 2014 17:52:44 +0200
Jochen Spieker <ml@well-adjusted.de> wrote:
> Hi folks,
>
> this looks very weird to me. My wheezy system claims that a filesystem
> is mounted, but the mount directory appears to be empty and umount
> fails because the filesystems is not mounted, after all:
>
> | # grep backup /etc/fstab
> | /dev/mapper/backup-decrypted /srv/backup ext4
> noatime,nodiratime,barrier=1,noauto,nodelalloc 0 0 |
> | # mount | grep backup
> | /dev/mapper/backup-decrypted on /srv/backup type ext4
> (rw,noatime,nodiratime,nodelalloc,data=ordered) |
> | # df -h /srv/backup/
> | Filesystem Size Used Avail Use% Mounted on
> | /dev/mapper/backup-decrypted 2.5T 1.8T 699G 72% /srv/backup
> |
> | # ls -la /srv/backup/
> | total 8
> | drwxr-xr-x 2 root root 4096 Oct 21 2011 ./
> | drwxr-xr-x 11 root root 4096 Oct 22 2013 ../
> |
> | # umount /srv/backup
> | umount: /srv/backup: not mounted
>
> I don't think it's important, but the filesystem is encrypted using
> LUKS on top of an LVM volume:
>
> | # grep backup /etc/crypttab
> | backup-decrypted /dev/mapper/backup2-lvol0
> none noauto,luks,cipher=aes-cbc-plain:sha256
>
> Interestingly, when I mount /srv/backup again, I can see its contents
> and umount it afterwards. But only once. Complete transcript:
>
> | # mount /srv/backup/
> |
> | # ls /srv/backup/
> | abattoir/ abattoir-winxp/ cupcake/ jigsaw/ lost+found/ mail/
> manowar/ _manual/ xenhost/ |
> | # mount | grep backup
> | /dev/mapper/backup-decrypted on /srv/backup type ext4
> (rw,noatime,nodiratime,nodelalloc,data=ordered)
> | /dev/mapper/backup-decrypted on /srv/backup type ext4
> (rw,noatime,nodiratime,nodelalloc,data=ordered) | | #
> umount /srv/backup |
> | # umount /srv/backup
> | umount: /srv/backup: not mounted
>
> Do you have any ideas what's wrong?
>
> Regards,
> J.
No. :-(
But I do have some thoughts.
First, if you're not unmounting /srv/backup as root, try doing so.
Next, before /dev/mapper/backup-decrypted can exist, something
(cryptsetup luksOpen) must create it. Look for that, in /etc/fstab and
elsewhere.
Also, something somewhere must input the LUKS filesystem's password.
As a reference, here's my shellscript for mounting an encrypted Blu-Ray:
==================================================
#!/bin/bash
discdev=/dev/sr0 #change as needed for system
udfmountpoint=/mnt/test
mapperdev=udf
udfloop=`sudo losetup -f`
sudo losetup $udfloop $discdev
sudo cryptsetup luksOpen $udfloop $mapperdev
sudo mount /dev/mapper/$mapperdev $udfmountpoint
echo Encrypted loop device is at /dev/mapper/$mapperdev or $udfloop.
echo Read files from $udfmountpoint
==================================================
When ready to unmount the disc, I work backwards, all as root or using
sudo:
* Unmount the disc from the mapper device.
* Eject the disc.
* use cryptsetup luksClose to close the encrypted device.
* Use losetup -d to delete the loopback device.
HTH,
SteveT
Steve Litt * http://www.troubleshooters.com/
Troubleshooting Training * Human Performance
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