Filesystem reporting wrong physical size after reboot

[Chis (Ian Chisholm)]

I have the following system:

Fedora Core 3
Kernel 2.6.12-1_1386_FC3smp
Apple Xraid attached via a Qlogic Fibre-channel card

Apple Xraid is full (14 500gb drives) made into 2x3.0Tb filesystems
(with 1 disk for RAID-5 parity in each). Ext3 filesystems created using
GNU parted and mkfs.

This system has been working perfectly since March (along with another
identical system, still running) but last night, a routine reboot had
the system come upclaiming that the disk is physically only 750 Gb in
size. Now it looks to me as if the disk has lost it's gpt label and is
32-bit wrapping the available disk size (effectively blocking 2Tb of
space). I can see the full file structure within parted, and can mount
the partition.

df -h shows: 
/dev/sda1             2.7T  2.0T  748G  73% /mnt

parted shows: 
(parted) print
Disk geometry for /dev/sda: 0kB - 3001GB
Disk label type: msdos
Number  Start   End     Size    Type      File system  Flags
1       32kB    801GB   801GB   primary   ext3         boot

Now I'd dearly love to get back the data on these partitions but at the
moment they think they are standard msdos-type partitions and won't let
me access 2Tb each of data.

I've google'd (and found: http://lkml.org/lkml/2005/2/9/150 which
describes my problem well, but no solution. Anyone got any ideas?

It looks to me as if the filesystem has replaced its gpt partition label
created originally by parted with a msdos partition label.

If I can create an identical partition on another machine on another
such RAID box can I dd the partition information and the superblock off
that and onto this one?

Ian

UNIX/Network Security Manager.