wojtek@3miasto.net writes:
> > >for the best performance... 32K per component may perform better.
> 
> please divide transfer rate by average access time. it's over 200kB for
> modern drives so there will be small difference between 16 and 32k read.

For the drives that I've played with, and the testing I've done w/ RAID 5, 
"bigger is better", until you reach the point where the data on a stripe 
is larger than MAXPHYS.  (There are some anomalous cases where that doesn't 
hold, but...)  For a 3-disk RAID 5, 32K seems the best.  For a 5-disk RAID 5, 
16K seems the best.  It's mostly all related to trying to get a MAXPHYS amount 
of data out to 'n' disks in parallel, without having to break a particular 
request down into multiple stripes...  Of course nothing beats actually 
building RAID sets w/ these various parameters on your own machines, and 
emperically figuring out the best parameters for your particular workloads.

Later...

Greg Oster