Re: [Bug-ddrescue] user-interface suggestions

[Richard Neill]

Dear Antonio,

Thanks for your reply.

> Richard Neill wrote:
> > 1. Make it more obvious that a logfile is strongly recommended. Change 
> > the man page synopsis to remove the [] from logfile. Thus
>
> Given that I use regularly ddrescue as a replacement for dd, I don't 
> like the idea of forcing logfile usage (or having to type an option to 
> override the logfile).
>
> I can add a warning to the man page saying something like "you should 
> use a logfile unless you know what you are doing".

OK - I agree about not forcing a logfile. I'd also suggest removing the 
[] brackets in the synopsis, i.e. replace "[logfile]" by "logfile", to 
indicate that most of the time, logfiles are needed. That was the visual 
cue that I myself was confused by.

> > 3. The -d option could perhaps be automatic?
>
> No. Using -d correctly in every case is an art. It can't be (easily) 
> automated.

The manual says:

     Use direct disc access to read the input file, bypassing the kernel
     cache. Hardware block size must be correctly set for this to work.
     Not all systems support this.

May I suggest a few more sentences of documentation would help? In the 
common case (a modern Linux or BSD system), is it fair to say that -d 
will work? If ddrescue is invoked with -d, but direct access isn't 
possible, will it fail gracefully, or will bad things happen? How can I 
find out whether the hardware block size is correctly set?

I think there are two separate issues here:

* When should -d as opposed to -n be used?
  I think this is what you refer to as an art.

* Is it appropriate to use -d at all? Are the block sizes correct? Does
  my system support this?
  That's what I suggest should be automated.


> > 4. Given that ddrescue will usually not terminate, it would be useful 
> > if ddrescue could print the time since it last recovered any data. 
> > Something such as "ddrescue has now been working for 8 hours without 
> > recovering any more data; you've probably got all you're going to get".
>
> Sounds well. I'll see what can be done.

Thanks.
> > 5. Lastly, for compatibility with regular dd, may I recommend graceful 
> > handling (or at least ignoring) of "kill -USR1"  ?
>
> I can easily handle it like SIGINT.

For regular dd,
    killall -USR1 dd
will make it print out statistics of where it has got to.

That's probably unnecessary here, but I think that USR1 should be 
trapped and *ignored* rather than treated the same as SIGINT.


Best wishes,

Richard