CentOS - Jun 2006 - Restoring data from disk w/ messed up partition tables

I had the electricity go out the other day. When my Centos 4.3 workstation came
up, I said yes when it got to the prompt "Unclean shutdown, force
filesystem check?" prompt.

It ground away for awhile and then said something about a bad superblock. Yikes!
I thought, that's a bad sign.

After a reboot, I got nothing but a grub> prompt.

I tried booting into rescue mode using the install CD, and got a message
"No valid partitions found". I tried to mount /dev/hda, and got a
message "no /etc/fstab found".

I tried running the install CD, and went into Disk Druid to see if it could see
any existing partitions on the drive, and got the message "Partition table
corrupted, must re-initialize disk, and reformat". Not a good sign. I
backed out at that point, not wanting to go beyond a point of no return.

I have about 4 years of archived e-mails, and some other misc stuff on that
drive that I don't want to lose.

Anyone have any suggestions what steps to take next?

Paul

On Tue, 2006-06-13 at 20:20 +0000, techlists at comcast.net
wrote:
> I had the electricity go out the other day. When my Centos 4.3 workstation
came up, I said yes when it got to the prompt "Unclean shutdown, force
filesystem check?" prompt.
> 
> It ground away for awhile and then said something about a bad superblock.
Yikes! I thought, that's a bad sign.
> 
> After a reboot, I got nothing but a grub> prompt.
> 
> I tried booting into rescue mode using the install CD, and got a message
"No valid partitions found". I tried to mount /dev/hda, and got a
message "no /etc/fstab found".
> 
> I tried running the install CD, and went into Disk Druid to see if it could
see any existing partitions on the drive, and got the message "Partition
table corrupted, must re-initialize disk, and reformat". Not a good sign. I
backed out at that point, not wanting to go beyond a point of no return.
> 
> I have about 4 years of archived e-mails, and some other misc stuff on that
drive that I don't want to lose.
> 
> Anyone have any suggestions what steps to take next?
The critical Q: do you *know* exactly what the partition settings were
before? If so, there is certainly hope. Manual partitioning can be done
using plain old fdisk or sfdisk. That gives some *possibilities*.

I won't bore you with details yet. I have recovered from this situation
with no special software (test and live) but I knew the layouts.

I'll be alert for your message.

Maybe there's some software that can help? Back in days of yore, I wrote
some "C" that looked at some 3B FDs and HDs and detected the start of
partition(s) (found super blocks, free inode lists, etc.). Maybe
something like that in the FS world?
> <snip sig stuff>
> Paul
HTH
-- 
Bill
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Unfortunately, I do *not* remember the original partition settings.

I was hoping to find a live CD that could fix such disasters (i.e.
systemrescueCD, or some such thing). I did find a Windows based program
that's supposed to do the trick. The evaluation edition lets you see if it
can see your lost data; you have to buy it ($79) to actually be able to recover
the data. This was at:

http://www.stellarinfo.com/linux-data-recovery.htm

I'm sure there must be an open source trick somewhere that should work
though.

Paul


 -------------- Original message ----------------------
From: "William L. Maltby" <BillsCentOS at triad.rr.com>

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Subject: Re: [CentOS] Restoring data from disk w/ messed up partition tables
Date: Tue, 13 Jun 2006 20:37:39 +0000
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techlists at comcast.net spake the following on
6/13/2006 1:54 PM:
> Unfortunately, I do *not* remember the original partition settings.
> 
> I was hoping to find a live CD that could fix such disasters (i.e.
systemrescueCD, or some such thing). I did find a Windows based program
that's supposed to do the trick. The evaluation edition lets you see if it
can see your lost data; you have to buy it ($79) to actually be able to recover
the data. This was at:
> 
> http://www.stellarinfo.com/linux-data-recovery.htm
> 
> I'm sure there must be an open source trick somewhere that should work
though.
> 
> Paul
Try testdisk. Here is a link to some info of which Live CD's have it.
http://www.cgsecurity.org/wiki/TestDisk_Livecd


-- 

MailScanner is like deodorant...
You hope everybody uses it, and
you notice quickly if they don't!!!!

As a follow up, I was able to find a *free* program to attempt to recover my
lost data. (I can't find the name of the program in a quick search, if
anyone's interested I'll check my system at home tonight and post it).

The software was able to see the lost partitions, but there was a huge amount of
CRC errors in trying to read the disk. So I suspect there was a failure of the
physical drive itself, more than just mere corruption of the partition table.
This was a drive that fell on the floor once, but seemed ok when I installed
Centos on it, so I left it in the system. Maybe it was already weak, and the
erratic electricity killed it for good.

I was able to recover quite a bit of lost data, but a lot of it appears to be
gone forever. This is a good reminder on the importance of keeping backups of
important stuff.

Paul




 -------------- Original message ----------------------
From: "William L. Maltby" <BillsCentOS at
triad.rr.com>
> _______________________________________________
> CentOS mailing list
> CentOS at centos.org
> http://lists.centos.org/mailman/listinfo/centos


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Subject: Re: [CentOS] Restoring data from disk w/ messed up partition tables
Date: Tue, 13 Jun 2006 21:09:35 +0000
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techlists at comcast.net spake the following on
6/15/2006 7:23 AM:
> As a follow up, I was able to find a *free* program to attempt to recover
my lost data. (I can't find the name of the program in a quick search, if
anyone's interested I'll check my system at home tonight and post it).
> 
> The software was able to see the lost partitions, but there was a huge
amount of CRC errors in trying to read the disk. So I suspect there was a
failure of the physical drive itself, more than just mere corruption of the
partition table. This was a drive that fell on the floor once, but seemed ok
when I installed Centos on it, so I left it in the system. Maybe it was already
weak, and the erratic electricity killed it for good.
> 
> I was able to recover quite a bit of lost data, but a lot of it appears to
be gone forever. This is a good reminder on the importance of keeping backups of
important stuff.
> 
> Paul
Another lesson... Never use a dropped hard drive for critical data. Some
drives still use glass for the platters, but even the aluminum platter drives
don't like more than a 1 or 2 G's in a fall. Hitting a hard floor from 3
feet
could easily hit 6 or more G's of force. Drives are cheap, recovery services
are expensive.

-- 

MailScanner is like deodorant...
You hope everybody uses it, and
you notice quickly if they don't!!!!