Date: Fri, 28 Sep 2001 08:18:01 -0600 From: Robert Gray <bob@cs.colorado.edu> To: "Daniel O'Connor" <doconnor@gsoft.com.au> Cc: Edwin Culp <eculp@EnContacto.Net>, freebsd-mobile@FreeBSD.ORG, kjerste soderberg <kjerstes@yahoo.com> Subject: Re: cloning laptop drives Message-ID: <200109281418.IAA30085@calypso.boulderlabs.com> In-Reply-To: Your message of "Fri, 28 Sep 2001 15:46:43 %2B0930."
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Yes, like Daniel says, large block sizes (I use 32K or 64K) and separate IDE controllers make a huge difference. You may as well use the "raw" devices to transfer directly into user space. One further tip, /usr/ports/misc/buffer, can double the speed because it forks into two processes connected via shared memory - a reader and a writer, each operating as fast as the disks can respectively read or write. In contrast, dd waits for a read to complete before starting a write. Buffer also prints progress so you know how long it will take. Here is approximately what I use: buffer -s 32k -S 1m </dev/rad0 >/dev/rad1 -s is the block size -S prints out progress "Daniel O'Connor" <doconnor@gsoft.com.au> Fri, 28 Sep 2001 15:46:43 +0930 says: > >On 28-Sep-2001 Edwin Culp wrote: >> AFAIK, the default for dd is one block at a time and that can take for ever >. >> You need to define the block size to something much larger. I have seen >> some >> cool formulas based on disk geometry but I never seem to remember them when >> I need them.:-( You might try something like >> >> dd if=/dev/ad0 of=/dev/ad1 bs=8192 >> >> Hopefully someone will give you a better number. > >I usually pick 64k when doing this.. > >Also, if those drives are on the same chain the performance is going to suck >really hard.. > >If you hit 'ctrl-t' you will get some info on dd's progress, and if you run >'systat -vmstat 1' and look at the bottom section you'll see the transfer >speeds. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-mobile" in the body of the message
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