Date: Thu, 28 Apr 2005 17:08:10 +0100 From: "Steven Hartland" <killing@multiplay.co.uk> To: "Eric Anderson" <anderson@centtech.com> Cc: freebsd-performance@freebsd.org Subject: Re: Very low disk performance Highpoint 1820a Message-ID: <070d01c54c0c$79550260$7f06000a@int.mediasurface.com> References: <069901c54bfd$2967ba40$7f06000a@int.mediasurface.com> <4270F648.5030501@centtech.com> <06d301c54c02$98ab5ce0$7f06000a@int.mediasurface.com> <42710594.2010308@centtech.com>
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----- Original Message -----
From: "Eric Anderson" <anderson@centtech.com>
> Correct - I misread the dd line. When you are doing the dd, what is
> your system busy doing? (top/ps info)
The machine is idle only me doing the test via an ssh session.
> What do you suspect?
I really dont know what it could be driver issue? iirc scott wrote / converted
this one from source direct form highpoint so maybe he could have some
useful imput here.
> Some info from one of my arrays:
>
> # dd if=/dev/zero of=./testfile bs=64k count=10000
> 10000+0 records in
> 10000+0 records out
> 655360000 bytes transferred in 3.581413 secs (182989226 bytes/sec)
>
> (unmount / mount filesystem)
> # dd if=./testfile of=/dev/null bs=64k count=10000
> 10000+0 records in
> 10000+0 records out
> 655360000 bytes transferred in 6.747707 secs (97123362 bytes/sec)
>
> # dd if=/dev/da0s1d of=/dev/null bs=64k count=10000
> 10000+0 records in
> 10000+0 records out
> 655360000 bytes transferred in 11.252226 secs (58242699 bytes/sec)
>
> Seems like the reads should be faster than the writes..
Hmm just tried the write and I get:
dd if=/dev/zero of=./testfile bs=64k count=10000
10000+0 records in
10000+0 records out
655360000 bytes transferred in 5.237026 secs (125139727 bytes/sec)
Which is 2.5 times quicker than read which is really just not
right.
Issue with /dev/null?
Steve / K
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