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Re: (S)ATA performance in FBSD 6.2/7.0
- To: "O. Hartmann" <ohartman_(_at_)_zedat_(_dot_)_fu-berlin_(_dot_)_de>, freebsd-performance_(_at_)_freebsd_(_dot_)_org, freebsd-questions_(_at_)_freebsd_(_dot_)_org
- Subject: Re: (S)ATA performance in FBSD 6.2/7.0
- From: "R. B. Riddick" <arne_woerner_(_at_)_yahoo_(_dot_)_com>
- Date: Fri, 2 Mar 2007 02:35:56 -0800 (PST)
--- "O. Hartmann" <ohartman_(_at_)_zedat_(_dot_)_fu-berlin_(_dot_)_de> wrote:
> Before digging into this problem deeper with benchmarks, could anyone
> explain why FreeBSD reaches this 33 MB/s limit (sounds like UDMA 33
> defaults, but on both boxes nForce4 and ICH5 controller are recognized
> and show up with SATA300 or SATA150 capabilities, respective)? May I
> have some knobs I'm not aware of to tune disk performance?
I think, this 33MB/sec limit comes like this:
The regular copy process (I think u used "cp") reads with speed S from disk A
and writes with speed S to disk B. But: While it reads, it doesnt write AND
while it writes, it doesnt read.
So you might want to try this:
dd if=/diskA/fileA bs=128k | dd of=/diskB/fileB bs=128k
You could also try just to read or to write. Or to read&write with
The fish are biting.
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