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Hello Archers,
Not sure where to post this question so I'll try here. Would anyone know the FACTS why the command below runs super fast under Arch-2009.08 and Fedora-12 but runs very slow under FreeBSD 8.1?
Notice; I did not not specify a block size for neither OS, so according to the DD documentation it is reading/write 512 blocks at a time from an unbuffered device and as you see ARCH runs like a bat-out-of-hell, regardless.
The only thing I figure is ,,, ARCH-LINUX must be bumping up the default size with-out the user knowledge when no size has been specified by user. Would this be true?
I notices this tooooo many times in the pass but this time I documented it for proof because I thought it was my imagination most of the time. I use all three OS by dual-booting when needed, and I use the same code below so they can backup each other when I make configuration changes in either OS. Machine don't matter... old or new, P3 512MB RAM or Phenom-II-965-QUAD - 8GB RAM, same results.
Same Command:
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dd if=/dev/sda3 | gzip -c | split -b 3500m - /12/File-Name-dd-By-Arch-Linux.gz.
ARCH-2009 - 1,504,432,145,920 bytes - 150GB = 2118sec = 35min = 1/2 hour - 71 MB/s
dd if=/dev/ad4s3 | gzip -c | split -b 3500m - /12/File-Name-dd-By-FreeBSD.gz.
FBSD 8.1 - 1,504,432,145,920 bytes - 150GB = 16652sec = 277min = 4 1/2hour - 9033694 b/s
293,812,785 + 0 record in
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I learn that it's a BLOCK vs CHAR thing. Linux use BLOCKS.
I use ARCH to control all my HDD's ... Running GRUB and dd'ing to backup all partitions with Windows Vista, Windows-7, FreeBSD Packet filters and routers. If you use the command I posted it may have an issue if you turn on top during dd'ing a large partition. I been dd'ing with ARCH with success for over a year and will not be cash out any time soon. I just learn what to do and what not to do until it is fix. Don't mean to cross-websites but maybe the author would like to know.
Here's the story ...
http://www.daemonforums.org/showthread. … 6a2&t=5503
Last edited by sharris (2010-12-31 15:38:46)
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