Large Pool is an optional memory structure used for the following purposes :-   (1) Session information for shared server   (2) I/O server processes   (3) Parallel queries   (4) Backup and recovery if using through RMAN. The role of Large Pool is important because otherwise memory would be allocated from the Shared pool. … Read more

SMON :- System monitor process recovers after an instance failure and monitors temporary segments and extents. PMON :- Process monitor process cleans up processes and releases locks and resources after an abnormal termination of a process.