Herbert Graf wrote:
> On Wed, 2009-09-02 at 15:02 -0400, Rolf wrote:
>   
>> I have tested enough drives recently to know that the advertised speeds 
>> are in the right ballparks... I am getting close to 100MB/s on a RAID0 
>> array on linux (actually, I get more, and I just tested....):
>>
>>  dd if=/dev/zero of=/fast/junk bs=1024k count=1024
>> 1024+0 records in
>> 1024+0 records out
>> 1073741824 bytes (1.1 GB) copied, 10.1231 s, 106 MB/s
>>     
>
> Interesting, dstat seems to be wrong! I just tried your method and the
> drive I though was doing over 100MBps is actually only hitting about
> 60MBps. Is there something about dstat I don't understand?
>
> TTYL
>
>   
dstat is likely more accurate...

even my test is biased, because it hits the file-system cache... but, 
for large files you can get close numbers.... and 1Gig is somewhat large.

a more interesting observation is to use 'nmon', or iostat while writing 
to disk to see what the rate of transfer is... or use bonnie++

Rolf
-- 
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist