Re: Filesystem benchmarking for pg 8.3.3 server

On Aug 13, 2008, at 2:54 PM, Henrik wrote:
>> Additionally, you need to be careful of what size writes you're
>> using. If you're doing random writes that perfectly align with the
>> raid stripe size, you'll see virtually no RAID5 overhead, and
>> you'll get the performance of N-1 drives, as opposed to RAID10
>> giving you N/2.
> But it still needs to do 2 reads and 2 writes for every write,
> correct?

If you are completely over-writing an entire stripe, there's no
reason to read the existing data; you would just calculate the parity
information from the new data. Any good controller should take that
approach.
--
Decibel!, aka Jim C. Nasby, Database Architect decibel(at)decibel(dot)org
Give your computer some brain candy! www.distributed.net Team #1828