So I screwed up majorly when adding a new hard drive to a server. I accidentaly ran fdisk on an existing partition, it told me it was not recognized, and so I pressed w to write.

Now when I try to book I get the error:

ALERT! /dev/mapper/LI--MAIL-root does not exist. Dropping to a Shell!

Grub also tells me :

Partition hd0, msdos5: not a known filesystem.

Unfortunately this is a live server that I need back up and running as soon as possible. I have spend the last 2 hour scouring the web for help. Please if anyone has any idea on how I can get this working again please help.

  • 3
    It's time to restore the backup you made before you started this. – Michael Hampton Jul 3 '14 at 18:42
  • Lemme guess - no backup either? If that's the case, stop using the server immediately and send the drives into a professional data restoration company. – EEAA Jul 3 '14 at 18:42

First of all, don't rush it. Trying to get out of such a situation in a hurry is just going to cause more mistakes.

Don't let anything get written to the disk you got a problem with. You'd better let that server alone for now.

  • Find the documentation on your restore procedure.
  • Start restoring from backup onto a spare server.
  • Once you have a system running from the restored backups, assess the damage: How much data are you missing because it was written after the last backup was made.
  • Get some hardware to run the recovery procedure on. I recommend a new machine with a RAID6 system with a logical capacity that is four times the physical size of the media you are trying to recover.
  • Create a raw image of the corrupted disk as a file on the RAID6.
  • Put the corrupted disk aside again.
  • Create a copy of the disk image before trying to make any changes.
  • Start looking through the image for possible file system metadata. You need to figure out the exact starting position and size of the file system you need to recover.
  • If you don't know enough details about the actual structure of the file system you are trying to recover, get help from somebody who does.

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