Low HDD tranfer rate with FreeBSD 5.3-Release

Amandeep aman at chamkila.org
Mon May 9 12:13:47 PDT 2005


Dan Nelson wrote:

>In the last episode (May 09), Eric Anderson said:
>  
>
>>>Eric Anderson wrote:
>>>      
>>>
>>>>Amandeep wrote:
>>>>        
>>>>
>>>>>I am using Tyan S2098 MB with 160GB Maxtor ATA  Drive and the
>>>>>transfer rate is very low. FreeBSD 5.3-Release.
>>>>>Any ideas what is going on here.
>>>>>
>>>>>The transfer rate is about 15MB/s
>>>>>
>>>>>when I run
>>>>>#dd if=/dev/zero of=/usr/junk bs=8192
>>>>>          
>>>>>
>>>Shouldnt it be around 54MB/s for a regular IDE drive.
>>>      
>>>
>>What about other block sizes?  Also - you should paste your actual dd
>>output here too.
>>
>>What's the model number of that drive?  Maxtor claims (on one of
>>their 160G drives) 17.8MB/s from inner diameter disk and 35.6MB/s for
>>outer diameter for the 5400rpm drives.
>>    
>>
>
>Yes, try 64k instead of 8k, and also compare read speeds.  If you have
>the time (could take an hour or so), try "dd if=/dev/ad0 of=/dev/null
>bs=64k", run an "iostat 60" in another window, let the dd run through
>the entire disk, and compare the relative speeds from start to finish.
>
>For the DiamondMax 160, the sustained throughput should be 26MB -> 50MB
>as you go from inner to outer tracks.
>
>  
>

OK with the above dd

dd if=/dev/ad0 of=/dev/null bs=64k

it gives me 56MB/s. from the start.

Aman




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