© Pearson Education Limited, Chapter 16 Physical Database Design – Step 7 (Monitor and Tune the Operational System) Transparencies

© Pearson Education Limited, Chapter 16 - Objectives The importance of monitoring and tuning the operational system. How to measure efficiency. How system resources affect performance.

© Pearson Education Limited, Step 8 Monitor and tune the operational system To monitor operational system and improve performance of system to correct inappropriate design decisions or reflect changing requirements.

© Pearson Education Limited, Step 8 Monitor and tune the operational system Number of factors that may be used to measure efficiency: - Transaction throughput: number of transactions processed in given time interval. -Response time: elapsed time for completion of a single transaction. -Disk storage: amount of disk space required to store database files. No one factor is always correct. Typically, have to trade one factor off against another to achieve a reasonable balance.

© Pearson Education Limited, Step 8 Monitor and tune the operational system Must be aware how 4 main h/w components interact and affect performance: main memory CPU disk I/O network. Note that an improvement in one resource may effect an improvement in other resources.

© Pearson Education Limited, Step 8 Monitor and tune the operational system Main memory: Significantly faster than secondary storage. More main memory, faster applications will run. Should always have between 5%-10% main memory available. Need to understand how target DBMS uses main memory.

© Pearson Education Limited, Step 8 Monitor and tune the operational system CPU: Controls tasks of other system resources and executes user processes. Most costly resource, so needs to be correctly utilized. Want to prevent CPU contention (processes waiting for CPU). Need to understand typical 24-hour workload and ensure sufficient resources available for both normal and peak workload.

© Pearson Education Limited, Step 8 Monitor and tune the operational system Disk I/O: With any large DBMS, significant amount of disk I/O. Need to carefully design how data is organized on disk. Operating system Main database files Index files Recovery log file

© Pearson Education Limited, Step 8 Monitor and tune the operational system RAID (Redunadant Array of Inexpensive Disks): Arrangement of several independent disks organized to increase performance and improve reliability. Performance increased through data striping (data divided into partitions and distributed across disks). Reliability improved through storing redundant data across disks so redundant data can be reconstructed should disk fail.

© Pearson Education Limited, Step 8 Monitor and tune the operational system StayHome wish to hold pictures of video cover plus brief story line.