Re: multi-residency vs. single instance, multi-database

The short answer is "it depends." In our environment, we run Lawson financials as well as a few home-grown DB applications. Lawson's database runs on its own instance, on the same physical box as the other instances. This was a more complicated decision than just performance. Lawson "certifies" on certain versions of Informix, and we didn't want our home-grown applications to be bound to specific versions based on what Lawson deems appropriate, so we separated out our home-grown apps on different instances. In a more general case, if I've got two DBs for two major apps, should I put them on one instance or two? Again it depends on several factors, the most important one being access patterns. If users tend to run quick-hitter single-row updates/queries/inserts, etc., then you're probably okay putting them on one instance. It becomes a problem, however, when you're running reports, especially ones with PDQ turned on. Application 'X' can, in theory, suck up all the resources of the engine, and starve Application 'Y'. On the flip side of the coin, if App Y is fairly quiet anyway, then it might be better to allow App X to run away with the resources and finish more quickly. If you DO opt to put the two apps on the same instance, I'd strongly recommend placing their data on different dbspaces, preferably on different physical disks or disk sets. Hope This Helps, - Tom Girsch Database Systems Manager Arch Communications CHRIS COREY wrote in message <71qou4$61k$1@news.xmission.com>... > >We are getting ready to implement PeopleSoft Financials 7 >and HRMS 7, phased in over the next year. We are running Informix >Dynamic Server 7.30.UC3 under HP-UX 11. > >Our initial plan was to use Informix' multi-residency capabilities >to have one database instance for Financials and one database >instance for HRMS, both running on the same box. Our thought >was, we could tune the engines separately and any problems >which required one instance to be brought down would only affect >that instance and not the other instance. > >However, recently we are beginning to question the performance >of two separate instances compared to creating a single database >instance with two databases -- one for Financials and one for HRMS. >We're concerned that the cost of two competing instances for one >set of resources may require more overhead than creating and tuning >a single instance. > >I'm curious to know people's opinions on this topic (preferably for >any other PeopleSoft customers, but really anyone who has had >experience balancing two application databases on a single machine). >Another alternative is to have each instance running on a separate >machine, but based on constraints, we will have to run them both >on a single machine for at least the next year. > >Thanks in advance for any ideas/opinions/comments. > >Chris Corey >ccorey@icrr.com >Database Administrator >Illinois Central Railroad >