Re: Upgrade to big SUN box or RAC for data warehouse?

From: Tanel Poder <tanel_at_@peldik.com>
Date: Tue, 22 Jul 2003 23:10:47 +0300
Message-ID: <3f1d9a46$1_1@news.estpak.ee>

Hi!

No, 2 phase commit is used in transactions distributed between different databases.
RAC doesn't increase IO per se, but it allows to overcome CPU (and memory) bottleneck, thus allowing more IO to be done. But since you still operate with the same number of disks, they can't service any more IO requests. A disk with average 5ms seek time can service 20 IO requests per second, but if you got more and more requests coming, they will queue up and the queues will grow until you start having problems such are IO timeouts etc..

Tanel.

"Ryan" <rgaffuri_at_cox.net> wrote in message news:PTfTa.875$5b7.404_at_lakeread01...
> why would implementing RAC increase I/O? is that because of the 2 phase
> commit? So you have to write to multiple datafiles?
Received on Tue Jul 22 2003 - 15:10:47 CDT