Drive Imaging with dd

[Jim Rootham]

>On Thu, 2003-08-28 at 11:47, Lennart Sorensen wrote:
>> Have you looked at top while running dd with gzip?  Might be CPU
>> limited.
>>
>> Lennart Sorensen
>
>With gzip set anywhere between -2 and -7 I seem to get around 15-25%
>idle time, which seems to indicate that there's enough processor time.
>It does bounce around a lot though, anywhere between 97% to 60% use for
>gzip.
>

I would suspect (with almost no evidence) that you may be missing latency
windows (especially on write).  It would not take too many times for the disk
to have to spin (almost) all the way round to hammer the total transfer rate
pretty good.   If you could get more buffers in the pipe that might help.

Jim
--
The Toronto Linux Users Group.      Meetings: http://tlug.ss.org
TLUG requests: Linux topics, No HTML, wrap text below 80 columns
How to UNSUBSCRIBE: http://tlug.ss.org/subscribe.shtml