[mythtv-users] OT: lost partition table

[Rod Smith]

On 02/25/2013 10:59 PM, Paul Stillwell wrote:
> Pardon the interruption for a quick question that isn't directly
> about Mythtv. Last week I had a disk failure on my Mythtv system.
> After some investigation, it seems that the partition table is
> corrupted or missing for some reason (I can see the data on the disk
> using a hex dump tool). I plan to use dd to copy the disk to another
> brand new drive (of the exact same size) and then use something like
> 'xfs_repair' (it's an XFS partition) to try to repair the drive. Has
> anyone had any success at something like this? If so, what did you
> do? Any tips/tricks?

If the disk used the GUID Partition Table (GPT), it's possible that the 
backup partition data remains intact. If this is the case, you could use 
gdisk to try to recover the data. See the following page for details:

http://www.rodsbooks.com/gdisk/repairing.html

Most disks, though, use the older Master Boot Record (MBR) scheme, and 
some types of problems will wipe both the main and backup data on GPT 
disks. In these cases, TestDisk will often fix the problem:

http://www.cgsecurity.org/wiki/TestDisk

Ideally, TestDisk will detect the "signatures" of the filesystems and 
will be able to construct new partition table entries (or even an 
entirely new partition table), thus recovering the entire filesystem intact.

The xfs_repair utility won't be much good unless and until you can 
recover the partition table -- and once you've done that, repair might 
not even be necessary, depending on what caused the problem.

Good luck!

-- 
Rod Smith
rodsmith at rodsbooks.com