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

[Paul L Daniels]

On Fri, 21 Jun 2013 06:49:40 -0400
Scott D <address@hidden> wrote:


> >
> Are you using the -d option for direct disk access? I have noticed
> slow downs like that, but using the direct disk access option seemed
> to take care of that and resulted in much faster reads.

        I've tried with and without.  Without -d seems to be faster at
        this point.

Anyhow, I did a major hack job ( in the true spirit of *nix ;) ) and
created this little shell script to help me out;


-------------
RECOVERY_SIZE=1
while [ 1 -eq 1 ]; do

        ddrescue -v -f -s ${RECOVERY_SIZE}M /dev/sdd data.img data.log
        echo "Sleeping ..."
        sleep 1
        echo "Awake!"

        RECOVERY_SIZE=$(($RECOVERY_SIZE + 1))

done
-------------

With this simple script, exploiting the strange behaviour where the
data rate usually has a burst at the start, I've gone from 13KByte/sec
average to closer to 51KByte/sec average.  Doesn't sound like a massive
increase but that does mean I'll go from barely 1GB/day up to 4GB/day,
and thus this recovery process will actually be "doable" within a month.

Still would love to know the mechanism behind it all.


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