Re: Databse File layout on only 4 drives Ideas?

"Joel Garry" <joel-garry_at_home.com> wrote in message news:91884734.0301271412.19f50e14_at_posting.google.com...
> Mark Townsend <markbtownsend_at_attbi.com> wrote in message
news:<BA5775D0.6EBA%markbtownsend_at_attbi.com>...
> > in article AepY9.54719$L47.8070994_at_read2.cgocable.net, David Platt at
> > david-platt_at_cogeco.ca wrote on 1/24/03 9:26 PM:
> >
> > > I am quite curious as to why a couple of you have written off the idea
of
> > > splitting data and index across drives. This is a practise that I
have
> > > followed for a while and I am wondering why it is being written off so
> > > quickly
> >
> >
> > First check the following -
> > http://otn.oracle.com/deploy/availability/pdf/oow2000_same.pdf
>
> Which says: "Any access hot-spot that is smaller than a megabyte
> should fit comfortably in the database buffer cache. Therefore it
> will not create a hot-spot on disk."
>
> I've always had a problem with this statement. Wouldn't a db buffer
> cache hot-spot like this be a "dirty write" attractor, often flushing
> and making a hot-spot on the disk?

No, because there's no relationship between the adjacent-ness of blocks on disk and what DBWR decides to flush.

(Which, I hate to mention it, explains why indexes and tables don't necessarily have to be separated. They might be read together (or close in time together, anyway), but that doesn't mean they will be *written* similarly).

I didn't read the original link, however, so I may have taken your comments out of context.

HJR Received on Tue Jan 28 2003 - 00:16:12 CST