Date: Fri, 31 Oct 2008 16:44:12 +0100 From: Christoph Kukulies <kuku@kukulies.org> To: Jeremy Chadwick <koitsu@FreeBSD.org> Cc: Ivan Voras <ivoras@freebsd.org>, freebsd-questions@freebsd.org Subject: Re: fastest raw device copy? Message-ID: <490B27CC.4040507@kukulies.org> In-Reply-To: <20081031151307.GA34850@icarus.home.lan> References: <490AC650.3000904@kukulies.org> <20081031110159.GA30244@icarus.home.lan> <gef0dq$l8a$1@ger.gmane.org> <490B17D2.6010000@kukulies.org> <20081031151307.GA34850@icarus.home.lan>
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Jeremy Chadwick schrieb: > 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. > > The job just finished and I have a figure of the Ubuntu performance, with the unfortunate blocksize parameter though, so I think it isn't much worth. Anyway here is the figure of the above dd command copying 500GB to a WDC disk in an Icy box. 50010+1 Datensätze ein 50010+1 Datensätze aus 500107862016 Bytes (500GB) kopiert, 25787,9 s, 19,4 MB/s Will do that using FreeBSD next time. Thanks a lot so far. -- Christoph
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