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Date: Tue, 28 Mar 2006 11:15:45 -0600
From: Joe Koberg <joe@osoft.us>
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References: <HCEOIFALKKLBLJPENPNOMEMNCAAA.khaled@ipbill.com>	<17444.13967.998120.314837@bhuda.mired.org>	<200603281139.29588.doconnor@gsoft.com.au>
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Cc: freebsd-hackers@freebsd.org
Subject: Re: cloning a FreeBSD HDD
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soralx@cydem.org wrote:
>> On Saturday 25 March 2006 04:42, Mike Meyer wrote:
>>     
>>> One thing: 1m is a bit small for modern systems. Or for not-so-modern
>>> systems. Since nothing else is running, you might as well use all the
>>> memory you've got, or as big as you can get a process to be. 128m or
>>> more is perfectly reasonable.
>>>       
>> It won't go any faster..
>>
>> In a modern system the CPU is so much faster than the disk than anything above 
>> about 16k would be enough.
>>     
>
> I found 64k to be optimal (e.g, max performance) on most machines
>
>   
I heard its faster if you use two dd's; i.e:

    # dd if=/dev/ad0 bs=64k | dd of=/dev/ad1 bs=64k

allowing read and write to proceed in parallel.

Joe Koberg
joe at osoft dot us