数据库设计教程chap16.pptVIP

September 98 ? Pearson Education Limited, 2004 September 98 Chapter Name Chapter 16 Physical Database Design – Step 7 (Monitor and Tune the Operational System) Transparencies Chapter 16 - Objectives The importance of monitoring and tuning the operational system. How to measure efficiency. How system resources affect performance. 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. 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. 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. 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. 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. 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 i