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Old 11-17-2012, 11:50 PM   #1
Kustom42
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/dev/md0 superblock error!


Hey LQ,

Been away for a while overseas, came back working for a medical software company. The previous admin had basically sabotaged the DC and we had to reset all the root passwords.

There is a very old box running two 36GB seagate SCSI drives that is failing on reboot with a /dev/md0 superblock cannot be read error. I have seen this before and have been able to work around it.

Here is where we are at..

System was up and running.

I rebooted and went to grub added single to the end and put init=/bin/bash. the system booted as it should, I ran the the mount command with the -o rw,remount / option. I then rebooted the system and it is displaying a bad superblock error on /dev/md0.

I have access to the basic filesystem still, I looked at the /etc/mdadm.conf and it has /dev/sda2 and /dev/sdb2 as the devices in the array. I attempted to edit the grub line and boot directly to both of these on two different attempts, both of which resulted in a kernel panic.

I attempted to run e2fsck and did mdadm --scan and some other mdadm commands but to no avail.

I am pretty inexperienced with software raids as I normally run hardware layer raids. It is a raid1 software raid. One thing I do know about the previous admin is that any chance he could do something custom or different than standard he would. Many other systems have custom compiled packages, and wierd configs, etc..

I am pretty exhausted from trying to get this going for the passed 4 hours and I'm sure that I'm missing some info.

However, if someone can drop some knowledge bomb that solves this problem before later tomorrow morning and helps me avoid having to rebuild an entire system and fail over our entire internal DNS and some very old fax interfaces I will be extremely grateful. [Mod Edit: to remove reward promise]

I will be up all night researching this and can give any other info that may help solve the problem.

Thank you everyone for taking the time to read over this and try to help me!

- Kustom42

Last edited by TobiSGD; 11-18-2012 at 04:01 PM. Reason: remove reward, not allowed
 
Old 11-17-2012, 11:52 PM   #2
Kustom42
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The system is running a version of gentoo. Forgot to add that.
 
Old 11-18-2012, 04:55 AM   #3
TobiSGD
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Are you sure that this is a problem with the RAID, not with the file system on it?
If you boot into rescue mode with init=/bin/bash, what is the output of
Code:
dumpe2fs /dev/md0 | grep -i superblock
 
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Old 11-18-2012, 12:10 PM   #4
Kustom42
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It gives me the following error:

No such file or directory while trying to open /dev/md0
Could not find valid filesystem superblock
 
Old 11-18-2012, 02:27 PM   #5
Kustom42
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Replaced server. All signs point to filesystem being b0rked beyond repair.
 
  


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