Re: 10K vs 15k rpm for analytics

Francisco Reyes wrote:
> Going with a 3Ware SAS controller.
> Already have simmilar machine in house.
> With RAID 1+0 Bonne++ reports around 400MB/sec sequential read.

Increase read-ahead and I'd bet you can add 50% to that easy--one area
the 3Ware controllers need serious help, as they admit:
http://www.3ware.com/kb/article.aspx?id=11050 Just make sure you ignore
their dirty_ratio comments--those are completely the opposite of what
you want on a database app. Still seems on the low side though.

Short stroke and you could probably chop worst-case speeds in half too,
on top of that.

Note that 3Ware's controllers have seriously limited reporting on drive
data when using SAS drives because they won't talk SMART to them:
http://www.3ware.com/KB/Article.aspx?id=15383 I consider them still a
useful vendor for SATA controllers, but would never buy a SAS solution
from them again until this is resolved.

--
Greg Smith 2ndQuadrant US Baltimore, MD
PostgreSQL Training, Services and Support
greg(at)2ndQuadrant(dot)com www.2ndQuadrant.us