Chapter 8. Regular expression (정규 표현 식)
















Oracle Database 10g: Administration Workshop l


 - System Global Area (SGA) : Shared by all server and background processes
 - Program Global Area (PGA) : Private to each server and background process. There is one PGA for each process.
 The SGA includer the following data structure:
• Database buffer cache: Caches blocks of data retrieved from the database
    Pinned : Multiple sessions are kept from writing to the same block at the same time. Other sessions wait to access the block. (server process에 기록을 하고 있는것) 
    Clean : 재사용 할 수 있는 후보(Free의 후보)
    Free(사용 가능한 것) or unused(한번도 사용하지 않는 것)
    Dirty
• Redo log buffer: Caches redo information (used for instance recovery) until it can be written to the physical redo log files stored on the disk :: 데이터베이스 변경 기록 저장 (DML 정보와 변경 사항을 기억하고 있음)
• Shared pool: Caches various constructs that can be shared among users
• Large pool: Is an optional area that provides large memory allocations for certain large processes, such as Oracle backup and recovery operations, and I/O server processes
• Java pool: Is used for all session-specific Java code and data within the Java Virtual Machine (JVM)
• Streams pool: Is used by Oracle Streams

Oracle Instance Management (오라클 필수 프로세스... 하나라도 죽어버리면 데이터베이스가 죽어버리게 됨.)
An Oracle database server consists of an Oracle database and an Oracle instance. An Oracle instance is made up of memory structures, known as the System Global Area (SGA), and background processes that handle much of the behind-the-scenes work involved in running an instance. The most common background processes are the following:
. System Monitor (SMON): Performs crash recovery when the instance is started following a failure
. Process Monitor (PMON): Performs process cleanup when a user process fails (특정 접속만 끈긴 세션에 대해 rollback을 시켜주고, lock이 걸린 부분을 관리하는 management)
. Database Writer (DBWn): Writes modified blocks from the database buffer cache to the data files on the disk
. Checkpoint (CKPT): Updates all the data files and control files of the database to indicate the most recent checkpoint (어디까지 입력되어있는지 확인해서 syncronize 등을 맡는 역할)
. LogWriter (LGWR): Writes redo log entries to the disk (redo log 에서 가지고 있는 내용을 write 하는 management)
. Archiver (ARCn): Copies redo log files to the archival storage when a log switch occurs (relo 내용을 수시로 백업해주는 프로세서)
 . show sga : 현재 사용중인 용량 확인


Planning the Database
As a DBA, you must plan:
  • The logical storage structure of the database and its physical implementation:
    – How many disk drives do you have for this?
    – How many data files will you need? (Plan for growth.)
    – How many tablespaces will you use?
    – Which type of information will be stored?
    – Are there any special storage requirements due to type or size?
  • The overall database design
  • A backup strategy for the database

Management Framework
The three components of the Oracle Database 10g management framework are:
  • Database instance
  • Listener
  • Management interface
    – Database Control
    – Management agent (when using Grid Control)


데이터베이스가 꺼지면..
  1. $ lsnrctl start
  2. $ sqlplus / as sysdba
     SQL> startup
  3. $ emctl start dbconsole


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