ext3 + fs > 2Tbyte

Andreas Dilger adilger at clusterfs.com
Mon Oct 31 22:06:48 UTC 2005

On Oct 31, 2005  19:33 +1100, Vincent McIntyre wrote:
> This host is hooked up to an Apple Xserve RAID with a 2.3Tbyte ptn
> that was created by the same system that is now giving trouble.
> My problem is that mount (2.12-4.backports.org.1) fails to mount this
> partition. It worked fine before, but stopped working after a power
> outage. Before I was using mount version 2.11n-7woody1 (the stock debian
> 'woody' version). I upgraded to the backports.org version of mount after 
> this problem appeared, but it didn't help.
> The symptom is -
> # mount /dev/sdb1
> mount: wrong fs type, bad option, bad superblock on /dev/sdb1,
>         or too many mounted file systems
>         (aren't you trying to mount an extended partition,
>         instead of some logical partition inside?)

It sounds like you have overflowed the end of the 2TB device limit and
clobbered the beginning of your filesystem.  This can happen if the
SCSI driver, kernel, or even ext3 isn't handling offsets > 2^31 properly.
I know RH has only recently started supporting ext3 filesystems > 2TB,
and it isn't clear that all drivers handle this properly yet.

> # e2fsck /dev/sdb1
> e2fsck 1.35 (28-Feb-2004)
> Couldn't find ext2 superblock, trying backup blocks...
> e2fsck: Bad magic number in super-block while trying to open /dev/sdb1
> The superblock could not be read or does not describe a correct ext2
> filesystem.  If the device is valid and it really contains an ext2
> filesystem (and not swap or ufs or something else), then the superblock
> is corrupt, and you might try running e2fsck with an alternate superblock:
>      e2fsck -b 8193 <device>
> Trying e2fsck -b 8193 /dev/sdb1 gives the same result.

Please update your e2fsprogs to the latest.  You also need to use
"e2fsck -b 32768" (or multiple thereof) for such large filesystems.
I think newer e2fsprogs will print this message properly in that case.

Cheers, Andreas
Andreas Dilger
Principal Software Engineer
Cluster File Systems, Inc.

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