Oracle 11g Multiple instances

Question

I have been given a task to install oracle 11g on Dell T110 server which contains 16Gb ram and 1.5TB of disk space. It is running with - Oracle Enterprise Linux 5 (RH Kernel) X86-64-, I have successfully installed one db instance on this machine and now i need to create another 3 instances for this server. I belive i need to have 4 different oracle SID s for this. Iam not very familir with linux and even to get installed one instance took nearly 3/4 of a day. I need ur support to create 3 more instances of this db. please help me providing all the commands i should execute on shell. would the problem solve if i create 3 more linux users and install oracle db again for each user with different sids?

Answer 1

First off, are you certain that you need four separate database instances rather than four schemas in a single database? Ideally, you'd have only one Oracle database per server but would run multiple applications in multiple schemas in that single database. What other products (i.e. SQL Server) refer to as a "database" is similar in Oracle to a schema.

Assuming you do need four separate database instances, you don't need separate operating system users. You can use the same operating system user you used previously (generally "oracle"). When you're doing the install, you just need to choose a different Oracle Home for each database. I'm also assuming that you are setting the memory-related parameters appropriately during each install rather than relying on the defaults which will cause each database to use a substantial fraction of the 16 GB of physical RAM you have available. You'd need to ensure that the total memory allocated to all four database instances plus whatever RAM is required to run the operating system and whatever other applications you run on this server is less than the 16 GB of physical RAM available.