Date: Fri, 31 Oct 2008 16:01:58 +0100 From: Erik Trulsson <ertr1013@student.uu.se> To: Christoph Kukulies <kuku@kukulies.org> Cc: Ivan Voras <ivoras@freebsd.org>, freebsd-questions@freebsd.org Subject: Re: fastest raw device copy? Message-ID: <20081031150158.GA31106@owl.midgard.homeip.net> 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. > > An idea how I can check the current amount of transfered byed alongside > the running dd command? Or watch the current i/o rate? Just type a ^T on the terminal dd is running on. This will send a SIGINFO to dd which will cause it to print out that information to the terminal. -- <Insert your favourite quote here.> Erik Trulsson ertr1013@student.uu.se
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