Oracle: Free buffer wait

Data Block Cache lack free buffers

Tune by

Increase data blocks

Try to tune DBWR

ASYNC

If no ASYNC use I/O Slaves (dbwr_io_slaves)

Multiple DBWR (db_writer_processes)

Direct I/O

Improving Inefficient SQL

requesting large # of blocks

Finding a Free Block:

If the data block isn’t in cache

• Get a free block and header in the buffer cache
• Read it off disk
• Update the free header
• Read the block into the buffer cache

Need Free Block to Read in New Data Block