Re: [bug-ddrescue] ddrescue strange read behaviour

[Marco Marques]

Hi,
  Adding up some detail related to my "-b" usage flag.

  When I define value for the "-b" flag I am careful enough to choose
multiple of 512 values.
  So in my experiments and trials I started with 4096 and so on.
  I have settled with the value 10240 ... 
  Although I do not see any difference by using the "-d" ( direct disk
acess ) mode ..

  Most of the time I get this kind of ata error :

ata8.00: cmd c8/00:08:00:4b:f9/00:00:00:00:00/ed tag 0 dma 10240 in
              res 51/04:08:00:4b:f9/00:00:00:00:00/ed Emask 0x1 (device error)
 
With the value after the "dma" defined in the ddrescue -b flag evocation ...
   Although I get sometimes different entries mostly with "dma 4096 in" 
    
   Despite the fact that am I still no recovering any of the marked zones ... 
   So at the moment I still have 2.1 GiB of data to "scrap" ....
   and with the default block ( 512) and stopping for each badblock plus
powercycling manually the HDD  It would take an enormous amount of time ...
   Any idea how to speed things up are welcome ..  

   Thanks for the fast answers and support
   Marco Marques

> > Although this weekend I started fiddling a little bit with the "-b  
> > " flag, order to mark some bad parts ...
> >    As far as I tried it is working as expected as I get more bad  
> > blocks marked faster ( bigger volume ) at the expense of not  
> > recovering the data.
> >    Can I use that way or I am doing it completly wrong ?
>   You are doing it completely wrong. :-)
>   '-b' must be (a multiple of) the real sector size, or all reads  
> will instantly fail in direct disc access mode.