Transaction Server Processes (Cont.) Database writer process Output modified buffer blocks to disks continually Log writer process Server processes simply add log records to log record buffer Log writer process outputs log records to stable storage. ■Checkpoint process .Performs periodic checkpoints Process monitor process Monitors other processes,and takes recovery actions if any of the other processes fail E.g.aborting any transactions being executed by a server process and restarting it Database System Concepts-7th Edition 20.8 ©Silberscha乜，Korth and SudarshanDatabase System Concepts - 7 20.8 ©Silberschatz, Korth and Sudarshan th Edition Transaction Server Processes (Cont.) ▪ Database writer process • Output modified buffer blocks to disks continually ▪ Log writer process • Server processes simply add log records to log record buffer • Log writer process outputs log records to stable storage. ▪ Checkpoint process • Performs periodic checkpoints ▪ Process monitor process • Monitors other processes, and takes recovery actions if any of the other processes fail ▪ E.g. aborting any transactions being executed by a server process and restarting it