Re: [Bug-ddrescue] --exit-on-slow ; NO DEVICE NAMES shown; skip+pause+reopen+skip_more_than_1Gb

[Antonio Diaz Diaz]

Dmitry Kostin wrote:
> I tried to use the newest version of ddrescue (1.22-pre3) and found some issues:
>
> 1) How should I compile it to force showing the drives' names when copying with 
> --ask:

Have you tried 'configure --enable-non-posix' ?


> 2) Being run on disk with slow areas with -a4194304 --exit-on-slow options, the 
> program works for !!! 30 seconds !!! before exiting. It copies at about 4 - 32 
> kb/s while the most of areas are being read at 15 Mb/s. So works skipping, too. 
> That is very bad for my case, because long-time readings of slow areas often 
> end up with read errors - and such readings may damage the rest of the disk 
> surface. I have found line 741 in rescuebook.cc:
>      rates_updated( false ), sliding_avg( 30 ), first_post( false ),
> - if I change 30 to 2 - will I get the program exit or skip after 2 seconds 
> instead of 30?

No. The right place to change is line 151 of rescuebook.h:

  bool slow_read() const
    { return ( t1 - t0 >= 30 &&         // no slow reads for first 30s
               ( ( min_read_rate > 0 && c_rate < min_read_rate &&
                   3 * c_rate < 2 * a_rate ) ||
                 ( min_read_rate == 0 && c_rate < a_rate / 10 ) ) ); }


> Or, can you please add one more option such as "sensitivity" or something to 
> set the interval (1-2-5-10-20-30) instead of built-in 30 seconds. (?)

Sure. Meanwhile you can modify the 30 in line 151 above.


> 3) The initial idea of skip+pause+reopen_input extension to 
> --min-read-rate=<time>[,pause] was very interesting. Can you implement it? 
> Maybe, it will fit my case better than --exit-on-slow. Not to invent a script to 
> pause and restart ddrescue with new -i -s parameters until exit.

Have you tried --reopen-on-error ? It also reopens the file after slow 
reads.


> 4) I want to skip that slow areas every 1280 Mb - but the program does not allow to 
> set -K<value>  to more than 1Gb. Can you please make a version that allows? Or, 
> maybe, give me an idea, where to patch the value(s).

I'll remove the limit on max_skipbs. Meanwhile you can increase 
'max_max_skipbs' in line 48 of rescuebook.h:

  enum { default_skipbs = 65536, max_max_skipbs = 1 << 30 };


> Thanks for your efforts and program!

You are welcome.