Re: [Bug-ddrescue] 10KB/sec data recovery rates - possible cause?

[Antonio Diaz Diaz]

Paul L Daniels wrote:
>         I switched over to an eSATA (powered) connection and I was
>         able to get 120K/sec until the drive hits the 4th head on the
>         platters which is dead.  Each time this happens the old
>         'quirk' that I've observed where the data rate doesn't recover
>         until you ctrl-C and restart is back.

I thought there were slow reads only, no errors. If there are errors 
then ddrescue begins to skip, and the read rate drops, but only until 
good data is found again.


>         Can you (Antonio) tell me where the data-rate/read-size
>         adjustment occurs [ when errors are returned ] in your C++ code,

Sure. Change the line 139 in rescuebook.cc from
      const int alignment = ( skip_size ? hardbs() : softbs() );
to
      const int alignment = softbs();


(Do the same to line 210 if you use reverse mode).

But (if it works for you) it is easier to make hardbs() == softbs() by 
using --cluster-size=1 and adjusting the sector size.


>         I just want to first try disabling the rate-adjustment to see if
>         I can start to isolate where this quirk is coming from.

Please, try it. I am also interested in making ddrescue work around 
drive problems like this.


Best regards,
Antonio.