sergey wrote:
> I got a disk array appliance of 8 disks 1T each (UltraStor RS8IP4). It
> will be used solely by PostgresQL database and I am trying to choose
> the best RAID level for it.
> ..
> Space is the least important factor. Even 1T will be enough.
Use RAID10, measure the speed of the whole array using the bonnie++ ZCAV
tool, and only use the fastest part of each array to store the important
stuff. You will improve worst-case performance in both sequential reads
and seek time that way. Drives are nearly twice as fast at their
beginning as they are at the end, and with only 8 drives you should be
able to setup a RAID10 array with all the fast parts aligned.
--
Greg Smith 2ndQuadrant US greg@2ndQuadrant.com Baltimore, MD
PostgreSQL Training, Services, and 24x7 Support www.2ndQuadrant.us
"PostgreSQL 9.0 High Performance": http://www.2ndQuadrant.com/books
