Managing database instance. Management Framework Oracle Database 11g Release 2 management framework has 3 components: – Database instance – Listener –

Managing database instance

Management Framework• Oracle Database 11g Release 2 management

framework has 3 components:– Database instance – Listener– Management interface

ListenerDatabase Control

ManagementAgent

Management interface

or

When using grid

Each of these components must be started before you can use the services of the component and must be shut down cleanly when shutting down the server hosting the Oracle database.

Database Startup

Incremental Startup• Nomount

– Server parameter file is read• Mount

– database is located. – Control file is required– redo and data files are opened

• Open– data and redo log files– start recovery if needed/ open– Listener is open and ready to accepts requests.– Consistency check by SMON (then periodic)– PMON monitor users

Starting Up an Oracle Database Instance: NOMOUNT

OPEN

MOUNT

NOMOUNT

SHUTDOWN

Instance started

STARTUP

initialization file is readMemory structures are createdOracle processes are started

Starting Up an Oracle Database Instance:MOUNT

OPEN

MOUNT

NOMOUNT

SHUTDOWN

Control file opened for this instance

Instance started

STARTUP

Starting Up an Oracle Database Instance: OPEN

OPEN

MOUNT

NOMOUNT

SHUTDOWN

All files opened as described by the control file for this instance

Control file opened for this instance

Instance started

STARTUP

Quick Descriptions

• Instance/database• Initialization file contains operating parameters for

instance/database– Spfile (dynamic)– pfile

• Control file binary file containing info on active database– Redo logs– Check point– datafiles

• Controlfile and redo log files protect data file

Shutdown

• Can be done incrementally• Must know how shutdown effects existing

connections.• Normal : wait until all transactions disconnect• Immediate: smon rolls forward committed

transactions• Transactional: Uncommitted transactions

continue• Abort : like power cut!!!

Shutdown Modes

Shutdown modes:• A = ABORT• I = IMMEDIATE• T = TRANSACTIONAL• N = NORMAL

Shutdown Modes A I T N

Allows new connections No No No No

Waits until current sessions end No No No Yes

Waits until current transactions end No No Yes Yes

Forces a checkpoint and closes files No Yes Yes Yes

Shutdown OptionsDuring:

SHUTDOWN NORMALorSHUTDOWN TRANSACTIONALorSHUTDOWN IMMEDIATE

Consistent database

On the way down:• Uncommitted

changes rolledback, forIMMEDIATE

• Database buffer cache written todata files

• Resources released

On the way up:• No instance

recovery

Shutdown OptionsDuring:

SHUTDOWN ABORTorInstance failureorSTARTUP FORCE

Inconsistent database

On the way down:• Modified buffers

not written to data files

• Uncommitted changes not rolled back

On the way up:• Online redo log

files used to reapply changes

• Undo segments used to roll back uncommitted changes

• Resources released

Overview of Primary Components

Instance

SGA

Redo logbuffer cache

Shared pool

Data Dict.cache

Librarycache

DBWRSMONPMON CKPTLGWR Others

Userprocess

Serverprocess

PGA

Control files

Data files Archived

log filesParameter

file

Passwordfile

Redo log files

Database

Databasebuffer cache

Oracle Instance

• Is a means to access an Oracle database• Always opens one and only one database• Consists of memory and process structures

Background structures/processes

Memory structures

SGA

Redo logbuffer cache

Database buffer cache

Shared pool

DBWRSMONPMON CKPTLGWR Others

Data Dictionarycache

Librarycache

Instance

Oracle databaseThe physical structure of an Oracle database isdetermined by the operating system files thatprovide the actual physical storage for databaseinformation.• Control files• Data files• Redo log files

Controlfiles

Data files(includes

data dictionary)

Header

Onlineredo log

files

Oracle Database

Control files

Data files Archived

log filesParameter

file

Passwordfile

Redo log files

Oracle Database

Data File• Data files

• Binary• Data stored as oracle blocks

• OS blocks

• Largest files type• Actual data• Exist all the time• Extension is NOT important but usually .DBF• Data File Header

• First blocks of the data file (by default 64K)• Manage datafiles internal workings• Backup/recovery info• Free space infromation• File status detail

• Tempfile• Special type of data

file• Holds temporary

information• Space freed when

done/logout

Parameter Files

• Entries are specific to the instance being accessed• There are two kinds of parameters:

• Explicit: Having an entry in the file• Implicit: No entry within the file, but assuming the Oracle

default values

• Multiple files can be used for a single database to optimize performance in different situations.

SPFILE spfileSID.ora

• Binary file with the ability to make changes persistent across shutdown and startup

• Maintained by the Oracle server• Records parameter value changes made with

the ALTER SYSTEM command• Can specify whether the change being made is

temporary or persistent

• Values can be deleted or reset to allow an instance to revert to the default value

• Can be dumped to text file for manual editing

PFILEinitSID.ora

• Default location is $ORACLE_HOME/dbs.• The PFILE is a text file that can be modified with an

operating system editor.• Modifications to the file are made manually.• Changes to the file take effect on the next startup.

Not dynamic

PFILE Example# Initialization Parameter File: initdb01.ora

db_name = db01

instance_name = db01

control_files = ( /u03/oradata/db01/control01db01.ctl,

/u03/oradata/db01/control02db01.ctl)

db_block_size = 4096

db_block_buffers = 500

shared_pool_size = 31457280 # 30M Shared Pool

db_files = 1024

background_dump_dest = /u05/oracle11g/admin/db01/bdump

user_dump_dest = /u05/oracle11g/admin/db01/udump

core_dump_dest = /u05/oracle11g/admin/db01/cdump

undo_management = auto

undo_tablespace = undtbs

. . .

Initialization Parameter Files (continued)

• Types of Values for Initialization Parameters• The Oracle database server has the following

types of values for initialization parameters:• Boolean• String• Integer• Parameter file• Reserved• Big Integer

Initialization Parameter Files (continued)

Derived Parameter Values• values are calculated from the values of other

parameters.• Do not alter values for derived parameters. If you do,

the value that you specify overrides the calculated value.

Example• The default value of the SESSIONS parameter is

derived from the value of the PROCESSES parameter.• If the value of PROCESSES changes, the default value

of SESSIONS changes as well unless you override it with a specified value.

Initialization Parameter Files (continued)

Operating System–Dependent Parameter Values• values or value ranges of some initialization

parameters depend on the host operating system.

Example• DB_FILE_MULTIBLOCK_READ_COUNT parameter

specifies the maximum number of blocks that are read in one I/O operation during a sequential scan; this parameter is platform dependent.

• The size of those blocks, which is set by DB_BLOCK_SIZE, has a default value that depends on the operating system.

Initialization Parameter Files (continued)Setting Parameter Values• Initialization parameters offer the most potential for improving

system performance. • Some parameters set capacity limits but do not affect

performance.

Example• If OPEN_CURSORS is 10, a user process attempting to open its

eleventh cursor receives an error. • Increasing the values of parameters may improve your

system’s performance• increasing most parameters also increases the system global

area (SGA) size.• A larger SGA can improve database performance up to a point

then swapping of SGA will degrade the perfromance

Control File The control file is a binary file that defines the

current state of the physical database.. • Loss of the control file requires recovery• Is read at MOUNT stage• Is required to operate• Is linked to a single database• Should be multiplexed

• Maintain a number of copies such that even if you lose a disk, you do NOT lose the control files

• Maintains integrity of database• Extension is usually .ctl or .con

• Any extension is ok

• Sized initially by CREATE DATABASE

Control files

Database

Simplified Initialization Parameters

DB_CACHE_SIZEDB_FILE_MULTIBLOCK_READ_COUNTSHARED_POOL_SIZE…

Advanced

CONTROL_FILESDB_BLOCK_SIZEPROCESSESUNDO_TABLESPACE…

Basic

•A basic parameter is defined as one that you are likely to set to keep your database running with good performance.

•All other parameters are considered to be advanced.•In the majority of cases, it is necessary to set and tune only the 30 basic parameters to get reasonable performance from the database.

•In rare situations, modification of the advanced parameters may be needed to achieve optimal performance.

•There are about 314 advanced parameters

Initialization Parameters: Examples

Parameter Specifies

CONTROL_FILES One or more control file names

DB_FILES Maximum number of database files

PROCESSES Maximum number of OS user processes that can simultaneously connect

DB_BLOCK_SIZE Standard database block size used by all tablespaces

DB_CACHE_SIZE Size of the standard block buffer cache

Initialization Parameters: Examples

System Global Area (SGA)

Shared poolDatabasebuffercache

Redo logbuffer

Streams poolLarge pool Java pool

KEEP buffer pool

RECYCLE buffer pool

nK buffer cache

PGA

Stack

Space

User

Global

Area

SGA_TARGET (Total size of all SGA components)

MMEMORY_TARGETT (Total size of system-wide usable memory)

Stack

Space

User

Global

Area

PGA

Initialization Parameters: Examples (continued)

•SGA_TARGET specifies the total size of all SGA components. If SGA_TARGET is specified, the following are automatically sized:

• Buffer cache (DB_CACHE_SIZE)• Shared pool (SHARED_POOL_SIZE)• Large pool (LARGE_POOL_SIZE)• Java pool (JAVA_POOL_SIZE)• Streams pool (STREAMS_POOL_SIZE)

• If these automatically tuned memory pools are set to nonzero values, the values are used as minimum levels by Automatic Shared Memory Management (ASMM).

•The following pools are manually sized components and are not affected by ASMM:

• Log buffer• Other buffer caches (such as KEEP and RECYCLE) and other block sizes• Fixed SGA and other internal allocations

•The memory allocated to these pools is deducted from the total available memory for SGA_TARGET when ASMM is enabled.

Initialization Parameters: Examples

Parameter Specifies

PGA_AGGREGATE_TARGET Amount of PGA memory allocated to all server processes

SHARED_POOL_SIZE Size of shared pool (in bytes)

UNDO_MANAGEMENT Undo space management mode to be used

Using SQL*Plus to View Parameters SQL> SELECT name , value FROM V$PARAMETER;NAME VALUE------------ ----------lock_name_space 2processes 150sessions 247timed_statistics TRUEtimed_os_statistics 0…

SQL>SHOW PARAMETER SHARED_POOL_SIZENAME TYPE VALUE------------------------------------ ----------- ---------------------shared_pool_size big integer 0

SQL> show parameter paraNAME TYPE VALUE------------------------------------ ----------- ---------------------fast_start_parallel_rollback string LOWparallel_adaptive_multi_user boolean TRUEparallel_automatic_tuning boolean FALSEparallel_execution_message_size integer 16384parallel_instance_group string…

Using SQL*Plus to View Parameters (continued)• Description of the view:

SQL> desc V$parameter Name Null? Type ---------------------------------------- ------- ------------- NUM NUMBER NAME VARCHAR2(80) TYPE NUMBER VALUE VARCHAR2(4000) DISPLAY_VALUE VARCHAR2(4000) ISDEFAULT VARCHAR2(9) ISSES_MODIFIABLE VARCHAR2(5) ISSYS_MODIFIABLE VARCHAR2(9) ISINSTANCE_MODIFIABLE VARCHAR2(5) ISMODIFIED VARCHAR2(10) ISADJUSTED VARCHAR2(5) ISDEPRECATED VARCHAR2(5) ISBASIC VARCHAR2(5) DESCRIPTION VARCHAR2(255) UPDATE_COMMENT VARCHAR2(255) HASH NUMBER

Using SQL*Plus to View Parameters (continued)

• V$SPPARAMETER: Displays information about the contents of the server parameter file. • If a server parameter file was not used to start the instance,

each row of the view will contain FALSE in the ISSPECIFIED column.

• V$PARAMETER2: Displays information about the initialization parameters that are currently in effect for the session, with each parameter value appearing as a row in the view. • A new session inherits parameter values from the instance-

wide values displayed in the V$SYSTEM_PARAMETER2 view.

• V$SYSTEM_PARAMETER: Displays information about the initialization parameters that are currently in effect for the instance.

Changing Initialization Parameter Values• Static parameters:

• Can be changed only in the parameter file• Require restarting the instance before taking effect• Account for about 110 parameters

• Dynamic parameters:• Can be changed while database is online• Can be altered at:

• Session level• System level

• Are valid for duration of session or based on SCOPE setting• Are changed by using ALTER SESSION and ALTER SYSTEM

commands• Account for about 234 parameters

Changing Initialization Parameter Values (contd)

Use “ALTER SYSTEM SET” statement to set or change initialization parameter values.

• SCOPE=SPFILE: The change is applied in the server parameter file only. No change is made to the current instance. For both dynamic and static parameters, the change is effective at the next startup and is persistent. This is the only SCOPE specification allowed for static parameters.

• SCOPE=MEMORY: The change is applied in memory only. The change is made to the current instance and is effective immediately. For dynamic parameters, the effect is immediate but not persistent because the server parameter file is not updated. For static parameters, this specification is not allowed.

• SCOPE=BOTH: The change is applied in both the server parameter file and memory. The change is made to the current instance and is effective immediately. For dynamic parameters, the effect is persistent because the server parameter file is updated. For static parameters, this specification is not allowed.

Changing Parameter Values: Examples

SQL> ALTER SESSION SET NLS_DATE_FORMAT ='mon dd yyyy';

Session altered.

SQL> SELECT SYSDATE FROM dual;

SYSDATE-----------jun 18 2009

SQL> ALTER SYSTEM SET SEC_MAX_FAILED_LOGIN_ATTEMPTS=2 COMMENT='Reduce from 10 for tighter security.' SCOPE=SPFILE;

System altered.

Contents of a control file

• Names and locations of data files and redo log files• Recovery Information• Backup Information• Checkpoint Information• Archiving Information• Database Name• Log History• Current logging information

Using Redo Log Files

Redo log files record all changes made to data and provide a recovery mechanism from a system or media failure.• Redo log files are organized into groups.• An Oracle database requires at least two groups. • Each redo log within a group is called a member.

Redo log files

Database

Redo Log Files

• Binary file• Store info from log buffer• LGWR writes into redo logs• Extensions .LOG or .RDO usually• Contains all information required to required to

recover lost data• Every SQL statement that change data can be reconstructed

• Multiplex (save mirrored copies) members• on different disks

Structure of Redo Log Files

Group 2 Group 3Group 1

Member

Disk 1

Disk 2Member

Member Member

MemberMember

• Redo logs are used in a cyclic fashion.• When a redo log file is full, LGWR will move to the next log group.

• This is called a log switch• Checkpoint operation also occurs• Information is written to the control file

Do not switch more frequently than 15-30 minutes

Forcing Log Switches and Checkpoints

• Log switches can be forced using the ALTER SYSTEM SWITCH LOGFILE command.

• Checkpoints can be forced using:• Setting FAST_START_MTTR_TARGET parameter• ALTER SYSTEM CHECKPOINT command

ALTER SYSTEM CHECKPOINT;

Archived Redo Log Files

Filled online redo log files can be archived.• Two advantages exist to archiving redo logs:

• Recovery: A database backup, together with online and archived redo log files can guarantee recovery of all committed transactions.

• Backup: Can be performed while the database is open.

• By default a database is created in NOARCHIVELOG mode.

Archived Redo Log Files • Archiving redo log files is accomplished by ARCn

(Archiver) or manually through SQL statements.• Whenever a redo log is successfully archived, an entry is

added to in the control file recording • the archive log name, • log sequence number, and • high and low SCN number

• A filled redo log file cannot be reused until • a checkpoint has taken place and • the redo log file has been backed up the ARCn process.

• Archived redo log files can be multiplexed.

• Archived redo log files must be maintained by the DBA.

Phases of database startup and shutdown

Management Framework• Oracle Database 11g Release 2 management

framework has 3 components:– Database instance – Listener– Management interface

ListenerDatabase Control

ManagementAgent

Management interface

or

When using grid

Listener.ora• is a SQL*Net configuration file used to configure Oracle

Database Listeners – required to accept remote connection requests

• Normally resides in the ORACLE HOME\NETWORK\ADMIN directory or in the directory define by the $TNS_ADMIN variable.

• consists of the following elements:– Name of the listener– Protocol addresses that the listener is accepting connection requests

on– Database services– Dynamic service registration, eliminates the need for static

configuration of supported services. However, static service configuration is required if you plan to use Oracle Enterprise Manager.

– Control parameters• Queue size• Receive buffer size, send buffer size

Sample Listener.ora# listener.ora Network Configuration File: /app/oracle/product/10.2.0/db_1/network/admin/listener.ora# Generated by Oracle configuration tools.

# SID_LIST_LISTENER =# (SID_LIST =# (SID_DESC =# (SID_NAME = PLSExtProc)# (ORACLE_HOME = /app/oracle/product/11.1.0/db_1)# (PROGRAM = extproc)# )# )

LISTENER = (DESCRIPTION_LIST = (DESCRIPTION = (ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC1)) (ADDRESS = (PROTOCOL = TCP)(HOST = localhost)(PORT = 1521)) ) )

How to modify listener

• Edit listener.ora• LsnrctlLsnrctl start listenerLsnrctl stop listenerLsnrctl status listener

• Net configuration assistant• Net manager

Starting and Stopping Database Control (Enterprise Manager)

Database Control stand-alone management console for databases that are not connected to the

Grid Control framework

Each database that is managed with Database Control has a separate Database Control installation From any one Database Control, you can manage only one database.

Navigate to the $ORACLE_HOME/bin directory if this directory is not in your operating system (OS) path. there are two $ORACLE_HOME locations if Grid Infrastructure is installed both contain the emctl utility. emctl utility should always be invoked using the Oracle database

$ORACLE_HOME and not the Grid Infrastructure $ORACLE_HOME.

Using Database ControlDatabase Control uses a server-side agent process. This agent

process automatically starts and stops when the dbconsole process is started or stopped.

Before using Database Control, ensure that a dbconsole process is started.

Command to start the dbconsole process:emctl start dbconsole

Command to stop the dbconsole process:emctl stop dbconsole

Command to view the status of the dbconsole process:emctl status dbconsole