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Date: Fri, 31 Oct 2008 15:36:02 +0100
From: Christoph Kukulies <kuku@kukulies.org>
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To: Ivan Voras <ivoras@freebsd.org>
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Cc: freebsd-questions@freebsd.org
Subject: Re: fastest raw device copy?
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Ivan Voras schrieb:
> Jeremy Chadwick wrote:
>   
>> On Fri, Oct 31, 2008 at 09:48:16AM +0100, Christoph Kukulies wrote:
>>     
>
>   
>>> What would be the fastest way to do that sector by sector copy? I'm  
>>> using dd right now,
>>>
>>> dd if=/dev/ad0 of=/dev/da0 bs=10000000
>>>       
>
>   
>> On the flip side, your blocksize (bs) there is quite high for no good
>> reason.  I'd pick something more like bs=64k or bs=128k.  The default
>> (512) is too small for what you want, but 10MBytes is silly.
>>     
>
> Not only that, but "10000000" isn't even correct - it needs to be a
> multiple of sector size. Generally, using suffixes will do the right thing:
>
> dd if=/dev/ad0 of=/dev/da0 bs=1m
>
>   
OK, I understand that 10000000 isn't good, I just thought it wouldn't 
harm. But if it is a transfer rate killer then I'd better think of 
typing ^C now. The command is running for 6 hours now.

An idea how I can check the current amount of transfered byed alongside 
the running dd command? Or watch the current i/o rate?


--
Christoph