Date: Fri, 31 Oct 2008 04:01:59 -0700 From: Jeremy Chadwick <koitsu@FreeBSD.org> To: Christoph Kukulies <kuku@kukulies.org> Cc: freebsd-questions@freebsd.org Subject: Re: fastest raw device copy? Message-ID: <20081031110159.GA30244@icarus.home.lan> In-Reply-To: <490AC650.3000904@kukulies.org> References: <490AC650.3000904@kukulies.org>
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On Fri, Oct 31, 2008 at 09:48:16AM +0100, Christoph Kukulies wrote: > Hi list, > > I'm considering using a bootable USB stick with FreeBSD to perform a > backup of my notebooks' > 500 GB hard disk to a physically identical (same make, same type, same > size) hard disk attached to USB. > > 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 > > but maybe there is a utility which does this faster or a larger buffer > size? Probably the limit will be > the USB 2.0 bus speed anyway? In general, what you're doing is correct for a block copy. There is nothing (that I know of) which is faster; you're copying 500GB of data (including the unused portion -- you *did* ask for a block copy), and this takes a long time. Be patient. 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. -- | 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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