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

I believe the biggest issue is the amount of memory on the machine and the sizes of the databases involved. There is a certain amount of overhead associated with an engine instance but if you have databases with any substantial size this overhead becomes a small percentage. A couple of other issues to keep in mind with multiple instances are: 1) Tape drives available for backups 2) Coordinating your backups 3) Kernal settings for shared memory and semaphores. -Bill > > 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