pitiful performance of an SATA150 drive

[Julian Elischer]

Brian Candler wrote:

>On Wed, Mar 01, 2006 at 12:05:17AM -0500, Mikhail T. wrote:
>  
>
>>I installed a new 500Gb SATA drive into my 6.1 system and am greatly
>>disappointed with its performance. Although straight reading is
>>Ok at around 32Mb/s, the writing is never more than 7Mb/s (as reported
>>by `systat 1 -vm' while running `cat < /dev/zero > /dev/ad8').
>>
>>I reported this a few months ago (running 6.0 then), and one of the
>>suggestions was, the drive is bad. Well, I'm seeing the same with its
>>replacement...
>>
>>Also, KNOPPIX-4.0.2 can write to the drive at 22Mb/s (using dd).
>>    
>>

I believe that linux uses bufferring in  their 'raw' disks so that you 
may be actually doing larger
reads and writes than you know.. (of course my knowledge of Linux is a 
bit old so
they may have changed that)

>
>Just to be clear: this is Knoppix running on the *same* machine as you've
>been testing FreeBSD? (In other words, you've not unplugged the drive and
>plugged it into a different PC or controller?)
>
>Aside: why are you using cat under FreeBSD, but dd under Knoppix? I'd use dd
>everywhere for consistency.
>
>Regards,
>
>Brian.
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>  
>