Re: autovacuum

On 9/21/07, Magnus Hagander <magnus(at)hagander(dot)net> wrote:
> On Thu, Sep 20, 2007 at 04:33:25PM -0500, Scott Marlowe wrote:
> > On 9/20/07, Robert Fitzpatrick <lists(at)webtent(dot)net> wrote:
> > > On Thu, 2007-09-20 at 16:38 -0400, Bill Moran wrote:
> > > > In response to Robert Fitzpatrick <lists(at)webtent(dot)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...

Yeah, I meant write back turned on...