How to Limit Rescue Domain (WAS Re: ddrescue 1.22)

[Shahrukh Merchant]

Hi Roberto,

Didn't see a response to the list to your question from a couple of 
weeks ago. Perhaps someone replied privately; if not, the ddrescue 
manual includes this paragraph:

==============================
Rescue domain
    Block or set of blocks to be acted upon (rescued, listed, etc). You 
may define it with the options '--input-position', '--size', and 
'--domain-mapfile'. The rescue domain defaults to the whole input file 
or mapfile.
==============================

So in your example you could use

ddrescue -f -i 20000000s /dev/sdb /dev/sdc mapfile

(along with whatever other options you may wish to use like -d or -v).

Note that while the size following -i (short for --input-position) is by 
default in bytes, ddrescue accepts the suffix "s" for sectors, as well 
as G for gigabyte, Gi for gigibyte,  etc., and in addition you can use 
Ms for megasector to make it more readable and avoid typing errors in 
the number of zeros. Note there is no space between the number and the 
suffix.

ddrescue -f -i 20Ms /dev/sdb /dev/sdc mapfile

Regards,

Shahrukh

On 2020-04-03 11:37 AM, Roberto Gini wrote:
> Hello thank you for ddrescue
>
> gently and kindly
>
> In the manual I can't  find (or I'm not able to understand which is it) the
> command to read only one portion of a certain RAW device
>
> I mean, e..g HDD 500GB is some 976M sectors it is e.g. /dev/sdb
>
> I will clone it on /dev/sdc
>
> but I want to skip the first 20.000.000 sectors more or less the first 10GG
>
> Which kindly is it the syntax to achieve this result?
>
> Thank you
>
> Roberto
> Verona
> Italy