Re: 4000GB partition becoming 1801GB after reboot?

[Isolationism]

First, let me say thank you very, very much for your help, Håkon. I
appreciate the time you took to reply very, very much.

> If you had just one partition that filled the whole disk, this should be
> not difficult to recreate.

I agree, however I would like to point out that the partition hasn't actually
been destroyed -- just horribly mangled. However I acknowledge the very high
likelyhood that this partition will have to be destroyed in order to create a
new, proper one -- hopefully then it can be recovered accordingly.

> To recreate a partition that have gone missing or been destroyed it has to
> start at the exact same sector that it was originally created.

The original partition simply consumed the whole disc from end to end, so I
shouldn't have to rack my brain to figure this out.

> The start/end numbers above are not exact sector numbers so I would like to
> have some more information. Could you run parted and print the complete
> partition table using units s, cyl and chs?

Absolutely:

-------
sectors
-------
Model: AMCC 9550SX-12M DISK (scsi)
Disk /dev/sdb: 7812415488s
Sector size (logical/physical): 512B/512B
Partition Table: msdos

Number  Start  End          Size         Type     File system  Flags
 1      63s    3517442203s  3517442141s  primary  xfs

---------
cylinders
---------
Disk /dev/sdb: 486300cyl
Sector size (logical/physical): 512B/512B
BIOS cylinder,head,sector geometry: 486300,255,63.  Each cylinder is 8225kB.
Partition Table: msdos

Number  Start  End        Size       Type     File system  Flags
 1      0cyl   218950cyl  218950cyl  primary  xfs

-----------------------
cylinders/heads/sectors
-----------------------
Disk /dev/sdb: 486300,95,2
Sector size (logical/physical): 512B/512B
BIOS cylinder,head,sector geometry: 486300,255,63.  Each cylinder is 8225kB.
Partition Table: msdos

Number  Start  End            Type     File system  Flags
 1      0,1,0  218950,165,58  primary  xfs


> Could you run fdisk with commands "x" and "p" to print the raw partition?

Yes, here it is:

Disk /dev/sdb: 255 heads, 63 sectors, 486300 cylinders

Nr AF  Hd Sec  Cyl  Hd Sec  Cyl     Start      Size ID
 1 00   1   1    0 254  63 1023         63 3517442141 83
 2 00   0   0    0   0   0    0          0          0 00
 3 00   0   0    0   0   0    0          0          0 00
 4 00   0   0    0   0   0    0          0          0 00


I have to assert that I really don't know what I'm doing with advanced
partitioning stuff; fdisk is all I have really ever used until I discovered
it wouldn't handle partitions in excess of 2TB.

In light of this fact, I have to disclose a couple extra points that may make
all the difference in the world:

1) I am fairly certain, but NOT dead positive, that I had set the disk label
to "gpt" when I created the array, following a brief guide found elsewhere on
the subject. This therefore begs the question of why the disk label is
showing as 'msdos' in

I am terrified that this post may apply to me:
http://www.mail-archive.com/address@hidden/msg02465.html

2) I am ashamed to say CONFIG_EFI_PARTITION=y was NOT set in the kernel when
I reboot the machine. It is defined now and the box has been rebooted (but it
makes no difference to the detected partition size etc.).

In light of these facts I'm wondering if it isn't possible that I created a
4TB partition in parted using an msdos table (despite the fact that this is
effectively illegal, which is the point of the link above).

I'm not precisely sure how this equates to data corruption, however, because
as I already stated the device ran fine for about a month (with no reboots)
and there were no cases of data corruption on the ~250GB or so data that was
on the drive (although I don't doubt if I had gone well over that amount
there would be corruption problems). This problem only became apparent after
a reboot, and it goes without saying that a couple successive reboots have
done little to improve the situation. :)

Thank you again for taking time out of your Sunday to help; I am grateful.

Cheers,
Kevin Williams