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  From: Daryl Tester <Daryl.Tester@iocane.com.au>
  To  : <wlsimes@tell.net.au>
        <linuxsa@linuxsa.org.au>
  Date: Fri, 29 Jun 2001 10:18:34 +0930

Re: dd time frame

<wlsimes@tell.net.au> wrote:

> I have an old Pentium 166mhz with 64mb ram in which I am performing a 
> dd if=/dev/hda of=/dev/hdc  between 2 x 30gb IDE hard drives.
[...]
> It's been slugging away now for at least three hours, this seems a 
> bit long,

You'd want to look at upping the blocksize; try:

  dd if=/dev/hda if=/dev/hdc bs=32k

as a start.  You could try larger block sizes, but then you start
hitting a definite performance elbow.

However, this won't give you a consistent snapshot if you've not
got the FS mounted read-only, and could make for some very funky
corruption.  If you don't want to go the read-only/single user
path, you'd probably be better off doing a tar or dump/restore
back to back.  All depends on what you're trying to achieve.


Regards,
  Daryl Tester

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