5 instances = too much ???

[rogerF]

Oracle People:

I've never had a machine with more than 3 instances. Now we're thinking of going from 3 - 5 instances on a machine that has 2Gig memory(Solaris 7 with Oracle 8i). None of the databases are too big- mostly support for apps like rational.

So- when do you hit the limit for instances ? Is there a rule of thumb ?

Thanks,

Roger

[Chris]

Roger,

this shouldn't be a problem. Just be careful with your sga sizing etc. We have a test machine and a training machine, running solaris with 5 and 6 instances respectively. shortly we'll be putting this into production. The production machine will be a Sun 450 with, I think 2gb ram, 4 CPUs.

Cheers

chris.

[jdorlon]

where I work we have an AIX server running about 60 financials instances. It all depends on how powerful your server is. For some servers, yeah, 5 would be too many. For others it is not. For a server with 2G of Ram, it could go either way depending on the databases and usage, I guess.

-John

[uday]

SGA and the amount of memory needed for your apps should make the decision. If you are running repositories for apps like rational, why not use a single instance with multiple schema's

Uday

[rogerF]

Oracle People:


I've gotten a healthy responce here and on the newsgroups- one reason why I like oracle.

It seems as if I should try to consuladate some of the schemas/tablespaces under one instance. We have Sybase and the sybase way of thinking is to have 1 set of procs with may sub-db's living in there. I assumed(I've been with Oracle 7 months) that you should create new instances for new DB's- it's what the wonderful(not) software dealers recommend(no, I don't trust them for oracle advise any more !).

What do you think of consoludating unlike schemas under 1 instance ? Yes- I would adjust the parameters for that instance.

-Roger

[tuvham]

I administer a sun 450 2GB mem 2 cpu with 36 oracle 7.3.4 databases - no problemo! The problem with having all "instances" in one database is that if the database hangs, all hangs. Its also easier to tune one database with one schema than to tune one database with 6 schemas if the schemas have very different characteristics.
But on the other hand, upgrading 36 databases to version x.x.x.x isn´t all that fun, and if you want to change something general, like turning autoextend off on all schemas, its a bit more work.
The only thing that will cause a problem when using a lot of databases in one machine (besides from the obvious) is that you have to increase some kernel parameters but it isn´t that hard.

/Tuve