hmm, got some answer via oracle docs but still have questions. Here's What I think large pool is in regards to MTS, it's used to cache processes sort area which are connected as shared server processes. shared pool are shared sql area and pl/sql.
as for as configuration,
mts_session is ratio of dispatcher to no. of connection.
still don't know diff between:
mts_dispatcher and mts_server. What function does mts_server servererd?
Think of the dispatcher as the traffic cop who tells the requests which shared server to go to. The shared server is the process that does the work on behalf of the user. There are a limited number of shared servers in an MTS configuration and each is shared by all users using MTS. In a dedicated server environment each session that gets established gets one process on the server. There are advantages and advantages to using MTS; choose wisely. (Note: an instance can be configured with shared server and dedicated servers.)
You need to think carefully about the sizing of your SGA when chosing MTS... UGA is stored in the SGA in MTS and stored in separate PGA in dedicated. Only use MTS if you HAVE to (in my humble opinion).