2 TB external HD does not mount any more. How to save it's data?

[Bas G. Roufs]

> The problem with dd is that it will fail on errors. I use gdd_rescue.
> I'm with Liam. Gddrescue has really shined for our uses, ... Worth a
> shot.

This article points in the same direction:
https://help.ubuntu.com/community/DataRecovery#Imaging_a_damaged_device.2C_filesystem_or_drive

In the mean time, I have installed gddrescue.

The question is now, what to do first after purchasing a new 3 TB external HDD. 
Do I need to first reformat it to EXT 4?

For the datarecovery, the page mentioned above proposes the following plan.

"(...) 

First you copy as much data as possible, without retrying or splitting 
sectors: 
ddrescue --no-split /dev/sdb1 imagefile logfile  

Now let it retry previous errors 3 times, using uncached reads: 
ddrescue --direct --max-retries=3 /dev/sdb1 imagefile logfile  

If that fails you can try again but retrimmed, so it tries to reread full 
sectors: 
ddrescue --direct --retrim --max-retries=3 /dev/sdb1 imagefile logfile

(...)"

My questions:
How to make sure that the old, damaged HDD will be recognised as sdb1 and the 
new one as, eg., sdb2?

How to EXACTLY-CORRECTLY indicate that I want to copy the image from the old 
disk (sdb1?) to the new one (sdb2)?

Can you recommend me any clear tutorial with clear steps for data recovery?




-- 


Bas G. Roufs
Utrecht, NL, EU.
E.: bas at basroufs.eu, M./SMS: +31 6 446 835 10.