Data from the Data file is added to the database buffer cache and then sent over network to the client.
All newly added data are placed in Default Buffer.If there is no space in default buffer then data is placed in Keep buffer...also data which is less frequently used are aged out from the default to recycle buffer..
We can have tablespace of multiple size block and hence we also have buffers of non default size.
DB_CACHE_SIZE determines size of default buffer
KEEP _CACHE_SIZE determines size of the keep buffer
RECYCLE _CACHE_SIZE determines size of the recycle buffer
and DB_BLOCK_SIZE determines size of the default data block..in above case its 8kb.
DB_CACHE_ADVICE if set to ON,READY collects statistics in v$ DB_CACHE_ADVICE view or else set to OFF
