Starting dbconsole process:
# emctl start|stop|status dbconsole

ORACLE_HOME/install/portlist.ini contains the listening port information.

Starting isqlplus listener
# isqlplus start|stop

listener.ora is used by these listeners.
tnsnames.ora is used by clients.

SPFILE is the initial parameter file in binary format.

An instance consists of a SGA and background processes.

SGA (System Global Area) consists of:
* Shared Pool: caching the sql which is shared among users
* Database Buffer Cache: caching the block.
* Redo Log Buffer: buffering the redo log until LGWR generates the redo log
* Large Pool: storing session info, IO slave, RMAN info etc.
* Java Pool
* Streams Pool: used by Oracle Streams

The major background processes are:
* PMON (Process MONitor)
* DBWn (DataBase Writer)
* LGWR (Log Writer)
* CKPT (Check Point)
* ARCn (Archiver)

The statistics in the memory is collected by the MMOM background process per every 60 mins in default, and the collected data is stored in AWR (Auto Workload Repository) in SYAUX for 7 days.