Re: 30 instances on one host

Daniel Morgan wrote:
>
> Sean M wrote:
>
> > It's not entirely academic - as I said in my other post, there are some
> > valid justifications for such a configuration (training, support,
> > etc.). But generally I agree - this sort of architecture is highly
> > specialized, and almost always used for situations where
> > performance/robustness/scalability are not the primary concern.
> >
> > Regards,
> > Sean
>
> I disagree. I can not believe there is any justification.
>
> I challenge anyone to give me a rationale whereby 10 instances makes more sense
> than 2 or 3.
>
> And lets make sure here that we are using the word 'instance' to mean 'instance'
> and not to mean 'datab ase'. You are talking about 10+ running Oracle
> executables. 10+ oracle_sids. 10+ * the number of threads in a single instance.

Well, as I said in my other post, a training class for Oracle would be a good example. Each student gets his or her own database (actual distinct Oracle database) for exercises so as not to conflict with the other students in the class (or in the next classroom over, for that matter). Each student needs his/her own because the class is on backup/recovery, or How to Build an Oracle Database, etc. (any sort of DBA-type class where each student needs complete control over his or her own database for the hands-on portion). Say 20 students per class, one server per class, 20 instances/databases per server. That makes far more sense than running 10 servers with 2 databases each for every class in terms of cost and managability, which clearly have a higher priority in this example than performance, etc. That's not to say performance isn't a consideration - you don't want the students waiting around. But you also don't want to spend the unjustifiable sums required to give each student his own server. Hence, like everything else, a compromise between cost/performance/managability must be struck.

Another example might be a support organization. Each telephone analyst might need a scratch instance to run simple tests on. You have 60 analysts. It would not make sense to buy 60 servers to run 60 test instances on. You buy 2 or 3 big ones and run 20 or 30 many small databases on each. Again, peformance takes a back seat to managability and cost, but that's perfectly acceptable and sane - the correct choice for this particular example.

But again, these are special cases. In the vast majority of situations, 20 or 30 databases on a single host would not be the correct, sane choice.

Regards,
Sean Received on Tue Jun 18 2002 - 01:06:32 CDT