From owner-freebsd-questions  Fri Jul  7 19:57:16 2000
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Date: Fri, 07 Jul 2000 19:59:40 -0700
From: Emmanuel Gravel <egravel@earthlink.net>
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Subject: Performance issues with dd
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As a backup measure, I'm using two hard drives of the same size,
but only mounting one, and I have a cron job that dd's one to 
the other every night. The drives are 18 GB U160 SCSI, on a
AHA-29160N. The whole process takes 45 minutes. A quick calc
tells me it should be finished at best in 2 minutes, at peak
rate. This is over a 20x difference.

Does anyone have any idea why it's taking so long? Is it just
dd that's the problem? The CPU is a PIII 650, and there's more
than enough memory to go, so I don't think the CPU would be
any kind of an impact here. Is there a better app out there
to do the job? I'm dumping one full raw device to the other,
not individual partitions. Could that be another problem?

Thanks for any input, I'm at a complete loss here.

Emmanuel


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