Multiple Instances

[nbiketi]

I have multilple instances running on the same host. I have all entries in the tnsnames.ora file. All are on port 1521, would this cause a problem.

[stsmuthu]

I don't think there could be any problem as long as your
hardware system supports the requirement.

[jmodic]

If you have one listener listening for all the instances on the same port you won't have any problem.

But if you have seperate listener for each of your instances (or at least more than 1 listener alltogether) and they are all set up to listen on port 1521 then you'll be able to start only one of them. In this case you have to assign each of them different port.

[pipo]

the file you should look at is the listener.ora file, not tnsnames.ora :
one listener can listen for multiple instances, and you can have multiple listeners on the same box, assuming all their listening ports are different ...
the question you should ask yourself is : will I be able to stop the listener for maintenance on 1 instance and not creating a problem since the other instances will not be available ... in this case : have several listeners, in the other case, one will be enough