Date: Sun, 30 Aug 1998 10:02:34 -0500 (CDT) From: Joel Ray Holveck <joelh@gnu.org> To: mike@smith.net.au Cc: avalon@coombs.anu.edu.au, hackers@FreeBSD.ORG Subject: Re: duplicating cd's with dd. Message-ID: <199808301502.KAA07242@detlev.UUCP> In-Reply-To: <199808292159.VAA10620@word.smith.net.au> (message from Mike Smith on Sat, 29 Aug 1998 21:59:08 %2B0000) References: <199808292159.VAA10620@word.smith.net.au>
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>> does anyone know if there are "preferred" parameters for using dd to >> copy cd's with ? > You can improve performance slightly with a larger block size (fewer > syscalls), but that's about it. I use 64K as an arbitrary figure; it > seems to run about as fast as the drive will go. I wrote a small script that tests each blocksize (with the laser off), and plots the number of blocks transferred before a buffer underrun, and the BPS rate. Since this is a slow system (Am486DX/4-100, AHA-1542, CDD-2600), then the timing is quite critical to me, and most block sizes would cause an underrun. I got a pretty clear pattern, indicating the optimal blocksize as 32k. Best, joelh -- Joel Ray Holveck - joelh@gnu.org - http://www.wp.com/piquan Fourth law of programming: Anything that can go wrong wi sendmail: segmentation violation - core dumped To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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