Hi Team, My OEM shows buffer cache hit ratio as 28% and library cache as 99%. Another query shows different results for buffer cache. SQL> SELECT NAME,100-PHYSICAL_READS/(DB_BLOCK_GETS + CONSISTENT_GETS) FROM V$BUFFER_POOL_STATISTICS; NAME 100-PHYSICAL_READS/(DB_BLOCK_GETS+CONSISTENT_GETS) -------------------- -------------------------------------------------- DEFAULT 99.9072457 SQL> show sga Total System Global Area 252273320 bytes Fixed Size 434856 bytes Variable Size 150994944 bytes Database Buffers 100663296 bytes Redo Buffers 180224 bytes And my db_block_buffers show value as 0. but it should be the value of database buffers / db_block_size . SQL> show parameter db_block NAME TYPE VALUE ------------------------------------ ----------- ---------------------- db_block_buffers integer 0 db_block_checking boolean FALSE db_block_checksum boolean TRUE db_block_size integer 8192 Is really my buffer cache hits very low? Regards - Chirag