Date: Thu, 10 May 2001 08:04:02 -0500 From: Mike Meyer <mwm@mired.org> To: Chris Fedde <chris@fedde.littleton.co.us> Cc: questions@freebsd.org Subject: Re: Use DD to make image copy of dual boot drive? Message-ID: <15098.37314.356817.228427@guru.mired.org> In-Reply-To: <88873791@toto.iv>
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Chris Fedde <chris@fedde.littleton.co.us> types: > On Wed, 9 May 2001 19:35:37 -0500 Mike Meyer wrote: > | > I'm not sure about the devices and what would be a good block size. Do I > | > need to use 512 bytes? The disks say: 32-bit mult-block-16 so that that me > an > | > an "efficient" block size would be 16x512? Or would a track (63x512) be > | > better? > | > | As long as it's at least 512 bytes, things should work. On the other > | hand, the bigger you make it, the faster the copy will go, unless you > | force your system to start swapping. I used to do half-cylinder > | chunks, because a full cylinder would cause the 11/70 to start > | swapping. > +------------------ > > Using one of the dis performance testers like Iozone or bonnie can help you > figure out the optomal block size for your system. I've found that about > 4096 is optomal for my systems. Those typically measure throughput through the file system. In this case, you're not going through the file system. That invalidates the results for this case. <mike -- Mike Meyer <mwm@mired.org> http://www.mired.org/home/mwm/ Independent WWW/Perforce/FreeBSD/Unix consultant, email for more information. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
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