On Tue, Apr 28, 2009 at 01:30:59PM -0500, Kevin Grittner wrote: > Craig James <craig_ja...@emolecules.com> wrote: > > > After a reading various articles, I thought that "noop" was the > > right choice when you're using a battery-backed RAID controller. > > The RAID controller is going to cache all data and reschedule the > > writes anyway, so the kernal schedule is irrelevant at best, and can > > slow things down. > > Wouldn't that depend on the relative sizes of those caches? In a > not-so-hypothetical example, we have machines with 120 GB OS cache, > and 256 MB BBU RAID controller cache. We seem to benefit from > elevator=deadline at the OS level. > > -Kevin > This was my understanding as well. If your RAID controller had a lot of well managed cache, then the noop scheduler was a win. Less performant RAID controllers benefit from teh deadline scheduler.
Cheers, Ken -- Sent via pgsql-performance mailing list (pgsql-performance@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
