Re: How many instances on a server?

David Van Zandt wrote in message <3837787F.4E9FEC53_at_iquest.net>...
>Hi, I need some way to determine how many instances I can run on a
>server (HP-UX N-class, dual processor).

Trick question this is. To the Dark Side of the Force this will lead.

Seriously, that depends on numerous issues. The size of the instances ito of disk space, memory, users, complexity of queries and so on. The reasons for wanting to have seperate instances vs. using a single instance with well defined physical boundaries between non related schemas. Backup and restore issues. Oracle licensing. Listener configurations. MTS. Etc. Etc.

Simply willy nilly slapping on another instance on any machine, even if the machine is capable of handling it, is a Bad Idea (tm). Define the requirements first before deciding on a technical solution. And do not let pre-conceived definitions of what is a database and that get in the way either. Many users will insists on "I must and want have my OWN database!!", without having the faintest clue what an Oracle "database" (or instance) really is.

Let the user specify the requirements. Let the techies decide on how to implement it. Keep the techies out of business requirement definition and the users out of technical issues. Easier said than done I know...

>A related question, how might I
>judge how much SGA is consumed for all existing instances, and how much
>is left (for a new one)?

It's not just a question of memory, but total system resources on the machine. What about CPU usage? What about disk i/o performance? Etc. You should be able to run a few sar's to get a general idea of what the current resource load is on the machine.

regards,
Billy Received on Mon Nov 22 1999 - 07:44:08 CST