Re: autovacuum

On Thu, Sep 20, 2007 at 04:33:25PM -0500, Scott Marlowe wrote:
> On 9/20/07, Robert Fitzpatrick <lists@webtent.net> wrote:
> > On Thu, 2007-09-20 at 16:38 -0400, Bill Moran wrote:
> > > In response to Robert Fitzpatrick <lists@webtent.net>:
> > > Why does everyone leave of the IO subsystem?  It's almost as if many
> > > people don't realize that disks exist ...
> > >
> > > With 2G of RAM, and a DB that's about 3G, then there's at least a G of
> > > database data _not_ in memory at any time.  As a result, disk speed is
> > > important, and _could_ be part of your problem.  You're not using RAID
> > > 5 are you?
> >
> > Yes, using RAID 5, not good? RAID 5 with hot fix total of 4 drives. All
> > SATA 80GB drives giving me little under 300GB to work with.
>
> RAID5 optimizes for space, not performance or reliability.  It gets
> faster but less reliable as it gets bigger.  If you can afford the
> space RAID-10 is generally preferred.
>
> Note however that it is far more important for most general purpose
> servers to have a RAID controller that is both fast by nature (i.e.
> not $50.00) and has battery backed cache with write thru turned on.

Surely you mean with write thru turned *off*... Or write-back turned on.
But write thru turned on will make your battery unnecessary...

//Magnus