Describe MySQL's InnoDB buffer pool and its optimization.

Buffer pool caches table and index data in memory for faster access.

Optimization:
innodb_buffer_pool_size = 70-80% of RAM
innodb_buffer_pool_instances = 8-16

Monitoring:
SHOW ENGINE INNODB STATUS;
SELECT * FROM information_schema.INNODB_BUFFER_POOL_STATS;

Key metrics:
• Buffer pool hit ratio (>99%)
• Pages read/written
• Free pages available