Re: [Bug-ddrescue] Rescueing Dell HDD

[Katona Gábor]

  Hi Chris,

First STOP! I think (I know) you are really lucky with ddrescue dropping 
error messages and stopping. Your trials could have ruined all data 
(really and unrecoverably) on your external drive, so stop before 
understanding at least the basics.

When dealing with disks and partitions ddrescue can save a whole disk, 
partition or file, or a given part of it. The main point is that 
ddrescue can only save parts what you define. It doesn't know anything 
about your filesystem, it only sees the drive or partition as a sequence 
of bytes. This is the power of ddrescue, and in some sense the weekness 
of it. *If your drive is accessible from e.g. a live Linux disk (I guess 
it is), copy all your data to a safe place first!* After this you can 
install a new system and copy back your data. Alternatively if you want 
to clone your disk to another one, to use it as it was before, togther 
with dell hidden partitions, you can use ddrescue, but for this, you 
need a drive with capacity for the whole disk or partition. ddrescue 
cannot determine which part of the disk is in use by your data (and you 
also cannot do that), it will copy everything. Of course compression on 
the fly is possible, but no one can predict the compression ratio of 
your disk, so it may not fit in the 70Gb free space on your external 
drive, but you can try.

If your drive has no errors at the moment, you may not need ddrescue at 
all. ddrescues main strength is recovering data from disks/files with 
errors, effectively skipping them for saving most of the data first, 
than turning to the problems. Of course it is also extremely suitable 
for exact cloning, but you can have a look at partimage[1] or 
partclone[2] to copy only the parts that are in use.

You have to choose which method you want to try, but first, save all 
your data simply by copying with a live CD if possible. If after this 
you choose ddrescue to make exact copy of your drive, here you can get 
answers on how to do that with or without compression.

Regards,

Gábor

[1] http://partclone.org/
[2] http://www.partimage.org/