On Wed, 31 Oct 2001, Cheryl L. Southard wrote:
> Hi All,
>
> This HORRIBLE thing has happened twice to me under RedHat 7.1, and I
> am desperate for a solution.
>
> Basically, we have about 10 or so PCs running RedHat 7.1. Both times the
> partitions dissapeared, we were rebooting the computer. One reboot was
> a legitimate one with a "shutdown -h", and the other was a hard (evil)
> reboot by turning the power off.
>
> Both times, the disk partitioning disapeared on some, but not all of
> the disks on the computer. If we run "fdisk -l", no partitions are
> reported.
>
> Or if we run fsck on the device, we get this message:
> fsck /scr4
> Parallelizing fsck version 1.23 (15-Aug-2001)
> e2fsck 1.23, 15-Aug-2001 for EXT2 FS 0.5b, 95/08/09
> fsck.ext2: No such device or address while trying to open /dev/sda1
> Possibly non-existent or swap device?
>
>
> So we ran "fdisk <device>" and created a single primary partition on
> the disk because we generally put a whole disks into one big partitions
> for all our non-system filesystems. Then we type "e2fsck <device>"
> which reports that the SUPERBLOCK is munged like this:
>
> # e2fsck -n /dev/sda1
> e2fsck 1.23, 15-Aug-2001 for EXT2 FS 0.5b, 95/08/09
> e2fsck: Bad magic number in super-block while trying to open /dev/sda1
>
> 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>
>
> We also tried it on various alternate superblocks including 8192, 16384 and
> 32768, 98304, 163840 Then we ran "findsuper" on the disk to scan for any
> superblocks. But e2fsck doesn't work for any of THOSE superblocks, either.
>
> Here are my questions:
> 1. What is making these partitions dissapear?
> 2. What can we do to recover the data?
> 3. How can we prevent this in the future.
Here are mistakes you could have made -- I seem to have done it once.
Step 1: partition the disk /dev/sda with one big partition, /dev/sda1.
Step 2: Build a file system on the one big partition with something like
"mke2fs /dev/sda". The mistake is using /dev/sda instead of
/dev/sda1. You have just destroyed the partitioning.
Step 3: Mount /dev/sda instead of /dev/sda1. It works fine. There's no
need to partition a disk if it's only intended to be used as one
big partition, and partitioning it even has the disadvantage of
wasting some space.
Step 4: Forget the mistakes of steps 2 and 3, and try to mount or e2fsck
/dev/sda1. It looks like something "HORRIBLE" has happened.
If you did make the above mistakes, and didn't try to repartition
the disk, you're in good shape. Just mount /dev/sda, and all your data
will be there.
--
Steven Yellin
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