SGA components explaination

SGA components
database buffer cache: cache blocks of data retrieved from disk
redo log buffer: cache redo information until it can be written to disk
shared pool : cache various constructs that can be shared among different db users
large pool: optional area used for buffering large i/o requests in support of parallel query,shared server,oracle XA,and certain types of backup operations such as RMAN
java pool:holds session-specific java code and data within the java virtual machine
stream pool:used by oracle stream