advice about copy from disk to disk

[Scott Mitchell]

On Wed, May 28, 2003 at 10:10:19PM +0800, adrian kok wrote:
> Hi all
> 
> Can you give me advice: quicky copy from disk to disk 
> 
> I use command dd and it almost takes the whole day to
> copy 80G data! 
> dd if=seondary master of=secondary slave bs=1024 
> (Secondary master to secondary slave)?

1. Use a much larger block size.  I think 64k or 128k will be about as good
   as you can get, but you probably want to experiment to see what works
   best on your system.

2. Put the drives on separate cables if possible.  Most ATA drives are
   pretty dumb - I imagine your are hogging the bus so that you can't read
   and write simultaneously.

3. Make sure you have DMA turned on if the drives support it (man
   atacontrol) and that you're using 80-wire cables if your drives and
   controller can run at UDMA66 speed or faster.

Hope that helps,

	Scott

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