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

I have checked both the new and old System Administration: Informix Dynamic Server training manuals. I have also scanned through the online document CD. Nothing in there to guide me through the configuration of multiple instances. The kernel parameters at the beginning of the release notes show recommended kernel values for a single instance. Will these values work for multiple instances? I have also taken the Online Tuning course. Not much was mentioned in it either. I guess that multiple-instance is the exception not the norm. Therefore, the shortage of information. I have no problems setting up multiple instances. Making sure that they run without "tripping" over each other is my problem. Phuoc Ho Bill Ennis wrote: > If you have taken the Database System Admin class there is a chapter on it. > > Here is a brief summary of what you need to set: > > In the onconfig file: > --------------------- > The SERVERNUM parameter needs to be unique for each instance > > The kernal parameters > --------------------- > check the file in $INFORMIXDIR/release/ONLINE_7.X > suggested settings are the the top. > > -BIll > > > > > Are there any documents out there outlining how multiple residency should > > be configured (kernel, memory, etc.)? The admin. manuals only show how to > > setup - not how to configure. > > > > Phuoc Ho > > > > Bill Ennis wrote: > > > > > 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