Oracle Database 2 Day DBA 11g Release- P11

Oracle Database 2 Day DBA 11g Release- P11:Oracle Database 2 Day DBA is a database administration quick start guide that teachesyou how to perform day-to-day database administrative tasks. The goal of this guideis to help you understand the concepts behind Oracle Database. It teaches you how toperform all common administrative tasks needed to keep the database operational,including how to perform basic troubleshooting and performance monitoringactivities.
Nội dung trích xuất từ tài liệu:
Oracle Database 2 Day DBA 11g Release- P11 Proactive Database Monitoring This is the average number of active sessions waiting for user I/O. User I/O means that the workload originating from the user causes the database to read data from disk or write data to disk. Click the User I/O link to go to the Performance page to view potential problems inside and outside the database. ■ CPU This is the average active sessions using CPU. Click the CPU link to see a chart showing more detailed information about active sessions over time.6. View the Diagnostic Summary section, which includes the following information: ■ ADDM Findings This shows the count of ADDM findings from the most recent ADDM run. Click the number adjacent to the ADDM Findings link to go to the ADDM page. ■ Period Start Time This is the start time of the time period most recently analyzed by ADDM. It is shown only if there are ADDM findings. ■ Alert Log This is the timestamp of the most recent alert log entry that describes an ORA- error. Click the Alert Log link to go to the Alert Log Errors page, which shows a list of log entries that contain errors. ■ Active Incidents This shows the count of active incidents, which are occurrences of critical errors in the database. You are encouraged to investigate critical errors and report them to Oracle Support Services. Click the count to go to the Support Workbench home page. ■ Database Instance Health Click Database Instance Health to display the Database Instance Health page, which includes graphical timelines of incidents, ADDM findings, and alerts. You can use these graphs for identifying correlations between incidents and alerts generated and performance issues on the system.7. View the SQL Response Time section. This is the current response time of a tracked set of SQL statements as compared to the response time for the reference collection. A reference collection, or SQL Tuning Set, is set of SQL statements that represents the typical SQL workload on your production system. If the current response time and reference collection response time are equal, then the system is running as it should. If the current response time is greater than the reference collection response time, then one or more SQL statements are performing more slowly than they should. The lower the current response time, the more efficiently the tracked SQL statements are running. Click the SQL Response Time link to see response time metrics for the previous 24 hours. If the reference collection is empty, then click Reset Reference Collection to go to a page where you can create a reference collection. Monitoring and Tuning the Database 10-5Proactive Database Monitoring 8. View the Space Summary section. If the number adjacent to the Segment Advisor Recommendations label is not zero, it means the Segment Advisor has identified candidate segments for space defragmentation. Click the number to view recommendations for how to defragment these segments. 9. View the Alerts section, which includes the following items: ■ Category list Optionally choose a category from the list to view alerts only in that category. ■ Critical This is the number of metrics that have exceeded critical thresholds plus the number of other critical alerts, such as those caused by incidents (critical errors). ■ Warning This is the number of metrics that have exceeded warning thresholds. ■ Alerts table Click the message to learn more about the alert. 10. View the ADDM Performance Analysis section, if present. This section contains the following items: ■ Period Start Time This is the start time of the period most recently analyzed by ADDM. ■ Period Duration in minutes This is the duration of the period most recently analyzed by ADDM. ■ Instance name ■ ADDM findings table This ...