Oracle System Monitor Process (SMON) background process

The System Monitor (background) Process is responsible for database maintance. Its tasks include

• Manage temporary tablespace metadata
• Reclaim lost space by orphaned temporary segments
• Adjust size of undo tablespaces by onlining, shrinking and offlining undo segments (based on undo space usage statistics)
• Clean up data dictionary
• Maintains the SCN to time mapping table used to support Oracle Flashback features
• Update col_usage$
• instance recovery
• In a RAC environment, SMON can perform instance recovery for failed instances.