Disk Throughput test

Chuck Swiger cswiger at mac.com
Thu Oct 23 18:00:22 UTC 2008

On Oct 23, 2008, at 10:50 AM, Stephen Sanders wrote:
> Good point about the RAID.  It is set for RAID 5 as the data is  
> supposed
> to be protected.

RAID-10 provides somewhat better data protection, but less available  
space and better write performance especially for small writes.  (For  
big writes, RAID-5 can do OK also, but small writes tend to really  
degrade RAID-5 performance, down to an order of magnitude *less*  
throughput compared with a single raw drive.)

> Interestingly enough, diskinfo is telling me that the drive throughput
> is 175MB/s.  I'm guessing that this means diskinfo is a mixture of  
> reads
> and writes?

No, it should only be doing reads.  For best-case read performance,  
it's likely to be at or near:

   dd if=_your_disks_ of=/dev/null bs=_raid_stripe_size_

...or adjust bs up or down by factors of 2 and benchmark.


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