How to configure -n

The -n parameter is a critical parameter for database startups.
The -n is the parameter which governs one layer of allocation of resources from the operating system for expected number of connections to the database. If the -n is not configured correctly there will most likely be problems when attempting to connect to the database.

The -n parameter allocates resources for local (shared memory) connections as well as remote client connections. The -n MUST be large enough to account for all local connections and remote connections. It is usually safest to allocate a small amount higher than the expected amount of connections (between 10 and 15 more). One reason this is suggested is that there are a number of specialty processes or jobs which use a slot from the -n and must be accounted for but aren't considered by DBAs when performing these calculations. APW, BIW, AIW, promon sessions, online backup sessions, watchdog sessions all must be counted within the -n value.

The -Mn is the parameter which governs the total number of servers that are desired for remote connections.

Multiple brokers can be spawned to handle remote client connections. Each broker can be assigned a limit to the number of servers that the broker will spawn. Each
-Mpb amount will be subtracted from the -Mn amount. Each remote client broker beyond the primary broker will also require one slot in the number of servers.
Example:
If -Mn is 40 and there is a need to have a primary broker and two secondary brokers then immediately subtract 2 from the 40 since there will be two secondary brokers.
That leaves 38 servers to allocate among the 3 brokers using the -Mpb parameter on each broker startup command.

The -Ma governs the number of clients that will be allowed to connect to one remote client server.

When calculating the -n it is necessary to know the number of local connections expected and the remote connections.
The total remote connections can be calculated by adding up the -Mpb value * the
-Ma value for each broker defined for the database.

Example:
If the expected number of local (shared memory) connections is 100.
If the desired number of brokers for remote clients is 3.
If the first broker will have 10 servers and 5 clients per server.
If the second broker will have 5 servers and 5 clients per server.
If the third broker will have 20 servers and 2 clients per server.

Here would be the values necessary for -n, -Mn, -Mpb, -Ma
-n 215
-Mn 37
For the first broker -Mpb 10 and -Ma 5
For the second broker -Mpb 5 -Ma 5
For the third broker -Mpb 20 -Ma 2
Taking into consideration the advice to increase the -n between 10 and 15 beyond the expecting amount the preferred value would be -n 230.

The startups for those brokers would look like this:
proserve sports2000 -n 230 -Mpb 10 -Ma 5 -Mn 37
proserve sports2000 -Mpb 5 -Ma 5 -m3
proserve sports2000 -Mpb 20 -Ma 2 -m3