Ryan Wexler wrote:
One question I do have is this card has a setting called Read Policy which apparently helps with sequentially reads. Do you think that is something I should enable?
Linux will do some amount of read-ahead in a similar way on its own. You run "blockdev --getra" and "blockdev --setra" on each disk device on the system to see the settings and increase them. I've found that tweaking there, where you can control exactly the amount of readahead, to be more effective than relying on the less tunable Read Policy modes in RAID cards that do something similar. That said, it doesn't seem to hurt to use both on the LSI card you have; giving more information there to the controller for its use in optimizing how it caches things, by changing to the more aggressive Read Policy setting, hasn't ever degraded results significantly when I've tried.
-- Greg Smith 2ndQuadrant US Baltimore, MD PostgreSQL Training, Services and Support greg@xxxxxxxxxxxxxxx www.2ndQuadrant.us -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
