[dm-crypt] xfs and fstab. To HeinzDiehl, first of all.

Heinz Diehl htd at fancy-poultry.org
Sat Jan 9 13:14:50 CET 2010

On 09.01.2010, Si St wrote: 

> _dev_hdc6 	/dev/hdc6  		none 	luks

This is the correct line for your partitions in crypttab, if you wish to
be asked for a password in the booting phase to unlock the partition.
If there's a message telling you "unknown option luks", I would consider
it as a bug in the boot.crypto system unless proved otherwise and opened a
bug report for it. Is there a possibility to upgrade?

> /var/log/messages:
> Jan  7 17:19:51 linux-wh8s kernel: XFS: bad magic number
> Jan  7 17:19:51 linux-wh8s kernel: XFS: SB validate failed

This indicates a major problem with the XFS superblock. XFS can't operate
on this drive without having this fixed.

> /var/log/warn:
> This came from the trying to open xfs on a filecontainer (note Dec 17):
> Dec 17 15:22:54 linux-wh8s kernel: XFS: Filesystem dm-3 has duplicate UUID -
> can't mount

A process has already mounted the filesystem (or is attempting that right
now) and has reserved the uuid. You'll have to find out what's the cause.

> The /var/log/messages notified that the 'acl' was unknown as to the XFS:

> Jan  8 17:46:45 linux-wh8s kernel: XFS: unknown mount option [user_xattr].

These are illegal XFS mount options and can be the cause that the underlying
filesystem doesn't get mounted. As a starting point, Please read here:


> Now, the xfs-partition was opened and there was error message promptwise or in
> the /var/log/messages:

So I can consider your problem solved? That's fine!

> Could I also have specified better the mkfs.xfs commandline too?
> I just have done: mkfs.xfs /dev/hd..

That's a matter of opinion and circumstances. Here's what I'm using,
regardless of encryption:

 mkfs.xfs -f -l lazy-count=1,version=2 -i attr=2 -d agcount=6 /dev/xxx

In fstab, I mount with


Please keep in mind that the "nobarrier" option gives great speed and
latency, but could cause severe data loss in case of a crash or power
failure. My systems are backuped by an UPS. (And I can remember having
read "barriers not supported" in your logs, this means the same).

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