Re: performance on new linux box

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@2ndQuadrant.com   www.2ndQuadrant.us