Oracle Database 2 Day DBA 11g Release- P5

Oracle Database 2 Day DBA 11g Release- P5: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.
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Oracle Database 2 Day DBA 11g Release- P5 Instances: Oracle By Example Series See Also: ■ Oracle Database Performance Tuning Guide for more information about memory parameters and their tuning ■ About Memory Management on page 5-13Instances: Oracle By Example Series Oracle By Example (OBE) has a series on the Oracle Database 2 Day DBA guide. This OBE steps you through the tasks in this chapter, and includes annotated screenshots. To view the Instances OBE, in your browser, enter the following URL: http://www.oracle.com/technology/obe/11gr1_2day_dba/instance/instance.htm Managing the Oracle Instance 5-21Instances: Oracle By Example Series5-22 Oracle Database 2 Day DBA 6 Managing Database Storage Structures This chapter discusses using Oracle Enterprise Manager Database Control (Database Control) to view and manage the storage structures of your database. This chapter contains the following sections: ■ About Database Storage Structures ■ Viewing Database Storage Structure Information ■ Performing Common Database Storage Tasks ■ Managing the Redo Log ■ Managing Undo Data ■ Storage: Oracle By Example SeriesAbout Database Storage Structures An Oracle database is made up of physical and logical structures. Physical structures are those that can be seen and operated on from the operating system, such as the physical files that store data on a disk. Logical structures are created and recognized by Oracle Database and are not known to the operating system. The primary logical structure in a database, a tablespace, contains physical files. The applications developer or user may be aware of the logical structure, but is not usually aware of this physical structure. The DBA must understand the relationship between the physical and logical structures of a database. Figure 6–1 on page 6-2 shows the relationships between logical and physical structures. This figure also shows recovery-related structures that are optionally kept in the flash recovery area. See Flash Recovery Area on page 9-3 for more information. Managing Database Storage Structures 6-1About Database Storage Structures Figure 6–1 Oracle Database Storage Structures Oracle Database SYSTEM SYSAUX UNDO USERS TEMP Tablespace Tablespace Tablespace Tablespace Tablespace Logical Structures Physical Structures Control file Server Datafile Datafile Datafile Datafile Tempfile Password Parameter file file Online Redo Logs Flash Recovery Area * Archived Redo Logs * Archived Redo Logs present only after turning on log archiving (ARCHIVELOG mode) Oracle Database can automate much of the management of its structure. Oracle Enterprise Manager Database Control (Database Control) provides a Web-based graphical user interface (GUI) to enable easier management and monitoring of your database. To view a database storage structure, go to the Storage section of the Server subpage. You can click the links shown in Figure 6–2 to access the storage pages. Figure 6–2 Storage Options This section provides background information about the various database storage structures. It contains the following topics: ■ About Control Files6-2 Oracle Database 2 Day DBA About Database Storage Structures ■ About Online Redo Log Files ■ About Archived Redo Log Files ■ About Rollback Segments ■ About Datafiles ■ About Tablespaces ■ About Other Storage Structures See Also: ■ Viewing Database Storage Structure Information on page 6-10About Control Files A control file tracks the physical components of the database. It is the root file that the database uses to find all the other files used by the database. Because of the importance of the control file, Oracle recommends that the control file be multiplexed. In other words, the control file should have multiple identical copies. For databases created with Oracle Database Configuration Assistant (DBCA), three copies of the control file ...