Date: Sun, 2 Oct 2005 16:57:09 +0200 From: Patrick Proniewski <patpro@patpro.net> To: freebsd-performance@freebsd.org Subject: dd(1) performance when copiing a disk to another Message-ID: <7035DA0C-E43C-478B-9B1C-6A32545E5E63@patpro.net>
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Hi,
(carte mère supermicro
chip SATA Intel 6300ESB)
I run FreeBSD 5.4 on a PIV 3GHz (SuperMicro motherboard, Intel SATA
6300ESB chipset) with 2 SATA HDD. I'm in the process to duplicate the
boot HDD to the second HDD. I run dd for that:
# dd if=/dev/ad4 of=/dev/ad6 bs=1m
It yields to poor performances:
$ iostat -dhKw 1
(...)
ad4 ad6
KB/t tps MB/s KB/t tps MB/s
124.49 252 30.69 128.00 246 30.69
128.00 285 35.64 128.00 279 34.90
128.00 282 35.27 128.00 283 35.40
(...)
Is it normal that data rate won't go upper than 35/38 MB/s ?
HDDs are: ad4 -> Maxtor 80 Go 7200 rpm
ad6 -> Hitachi 80 Go 7200 rpm
one more question: is dd(1) a good way to duplicate a boot drive to
make a bootable spare disk ?
patpro
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