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Lesson 1

Lesson 1. Overview of Oracle8 Architecture. Objectives. Recognize the components of the Oracle8 architecture. Identify the purpose of each of the component types. Overview. A database administrator (DBA) must understand the Oracle Server architecture to effectively manage an Oracle database.

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Lesson 1

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  1. Lesson 1 Overview of Oracle8 Architecture

  2. Objectives • Recognize the components of the Oracle8 architecture. • Identify the purpose of each of the component types.

  3. Overview • A database administrator (DBA) must understand the Oracle Server architecture to effectively manage an Oracle database. • The DBA must understand the following components: • Processes • Memory structures • Files

  4. Overview • Processes • Memory Structures • Files

  5. Memory Structures • SystemGlobal Area (SGA)

  6. The Shared Pool • SystemGlobal Area (SGA) Shared Pool Shared SQL Areas (Library cache) Data Dictionary Cache

  7. The Database Buffer Cache • SystemGlobal Area (SGA) Shared Pool Database Buffer Cache

  8. The Redo Log Buffer • SystemGlobal Area (SGA) Shared Pool Database Buffer Cache Redo Log Buffer

  9. Snnn SMON LCKn Dnnn SNPn RECO Pnnn PMON CKPT DBWR LGWR Background Processes • SGA Redo LogBuffer Shared Pool Database Buffer Cache ARCH

  10. Snnn SMON LCKn Dnnn SNPn RECO Pnnn PMON CKPT DBWR LGWR User Processes • SGA Redo LogBuffer Shared Pool Database Buffer Cache ARCH UserProcesses

  11. Snnn SMON LCKn Dnnn SNPn RECO Pnnn PMON CKPT DBWR LGWR Server Processes • SGA Redo LogBuffer Shared Pool Database Buffer Cache ARCH Server Processes UserProcesses

  12. PMON SMON LCKn Snnn Dnnn SNPn RECO Pnnn DBWR CKPT LGWR ARCH An Oracle Instance • Oracle Instance • SGA Redo LogBuffer Shared Pool Database Buffer Cache Server Processes UserProcesses

  13. User Requests SGA • PGA • User • Session • Data Server Processes • Stack • Space UserProcesses User Request

  14. Configuration of the PGA • Server Processes • User • Session • Data • Stack • Space • PGA

  15. An Oracle Database Redo Log Files Control Files Datafiles

  16. Redo Log Files Log File 1 Log File 2 Log File 3

  17. Multiplexed Redo Log Files Group 1 Group 3 Group 2 Member A Member A Member A Disk 1 Member B Member B Member B Disk 2

  18. Control Files • All necessary database files and log files are identified in the control file. • The name of the database is stored in the control file. • A control file is required to mount, open, and access the database. • Synchronization information needed for recovery is stored inside the control file. • The recommended configuration is a minimum of two control files on different disks. • The parameter CONTROL_FILES identifies the control files.

  19. PMON SMON LCKn Snnn Dnnn SNPn RECO Pnnn DBWR CKPT LGWR ARCH The Parameter File • Oracle Instance • SGA Redo LogBuffer Shared Pool Database Buffer Cache Parameter File

  20. The Parameter File • SystemGlobal Area (SGA) Shared Pool Database Buffer Cache Redo Log Buffer SHARED_POOL_SIZE LOG_BUFFER DB_BLOCK_SIZE DB_BLOCK_BUFFERS

  21. The Alert File • All internal errors (ORA-600), block corruption errors (ORA-1578), and deadlock errors (ORA-60) that occur • Administrative operations (DDL), and Server Manager statements (STARTUP, SHUTDOWN, ARCHIVE LOG, and RECOVER) • The values of all non-default initialization parameters at the time the database and instance start

  22. The Trace Files • Contain information about internal errors detected by a server process or a background process • Are located in BACKGROUND_DUMP_DEST or USER_DUMP_DEST • Are created if SQL_TRACE = TRUE • Are created if SQL_TRACE is enabled for a session SQL> ALTER SESSION SET SQL_TRACE = TRUE;

  23. SMON LCKn Snnn Dnnn SNPn RECO PMON Pnnn DBWR CKPT LGWR Summary Oracle Instance • SGA Redo LogBuffer Shared Pool Database Buffer Cache ARCH UserProcesses Server Processes Oracle Database Parameter File Control Files Datafiles Redo Log Files

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