Date: Fri, 31 Oct 2008 08:13:07 -0700 From: Jeremy Chadwick <koitsu@FreeBSD.org> To: Christoph Kukulies <kuku@kukulies.org> Cc: Ivan Voras <ivoras@freebsd.org>, freebsd-questions@freebsd.org Subject: Re: fastest raw device copy? Message-ID: <20081031151307.GA34850@icarus.home.lan> In-Reply-To: <490B17D2.6010000@kukulies.org> References: <490AC650.3000904@kukulies.org> <20081031110159.GA30244@icarus.home.lan> <gef0dq$l8a$1@ger.gmane.org> <490B17D2.6010000@kukulies.org>
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On Fri, Oct 31, 2008 at 03:36:02PM +0100, Christoph Kukulies wrote: > 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. Six hours? Hmm... That seems too long, but of course the FreeBSD USB stack is involved, and a USB device in general. I would have assumed that copy should have finished after 2-3 hours tops. > An idea how I can check the current amount of transfered byed alongside > the running dd command? Or watch the current i/o rate? iostat or gstat (I'm willing to bet you prefer the latter) will get you what you want, more or less. -- | Jeremy Chadwick jdc at parodius.com | | Parodius Networking http://www.parodius.com/ | | UNIX Systems Administrator Mountain View, CA, USA | | Making life hard for others since 1977. PGP: 4BD6C0CB |
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