6. backup and recovery - cursuri automatica si...

Universitatea Politehnica Bucureşti - Facultatea de Automatica si Calculatoare

6. Backup and Recovery

10.01.2010 1Administrarea Bazelor de Date I


Outline

• Backup and Recovery Overview

• Instance and Media Recovery Structures

• Configuring the Database Archiving Mode

• Oracle Recovery Manager



Backup and Recovery Overview

• Describe the basics of database backup, restore and recovery• List the types of failures that may occur in an Oracle environmentList the types of failures that may occur in an Oracle environment• Define a backup and recovery strategy



Backup and Recovery Issues

• Protect the database from numerous types of failures

I M Ti B t F il (MTBF)• Increase Mean-Time-Between-Failures (MTBF)

• Decrease Mean-Time-To-Recover (MTTR)

• Minimize data loss



Categories of Failures

• Statement failure• Statement failure

• User process failure

• User error• User error

• Network failure

Instance failure• Instance failure

• Media failure



Causes of Failure

• System Crashes due to hardware or software errors, resulting in loss of main memoryin loss of main memory.

• Media Failure, such as head crashes or unreadable media, resulting in the loss of parts of secondary storageresulting in the loss of parts of secondary storage.

• Application Software Errors, one or more transactions fail due to the logical error of the program.g p g

• Human Destruction.



Causes of Statement Failures

• Logic error in an application

Att t t t i lid d t i t th t bl• Attempt to enter invalid data into the table

• Attempt an operation with insufficient privileges

• Attempt to create a table but exceed allocated quota limits

• Attempt an INSERT or UPDATE to a table, causing an extent

to be allocated, but with insufficient free space available in the

tablespace



Resolutions for Statement Failures

• Correct the logical flow of the program

M dif d i th SQL t t t• Modify and reissue the SQL statement

• Provide the necessary database privileges

• Change the user’s quota limit by using the ALTER USER

command

• Add file space to the tablespace

• Enable resumable space allocation



Causes of User Process Failures

• The user performed an abnormal disconnect in the session

The user’s session was abnormally terminated• The user s session was abnormally terminated

• The user’s program raised an address exception, which terminated the sessionterminated the session



Resolution of User Process Failures

• The PMON process detects an abnormally terminated user

processprocess

• PMON rolls back the transaction and releases any resources

d l k b i h ld b itand locks being held by it



Possible User Errors

SQL> DROP TABLE employees;p y

SQL> TRUNCATE TABLE employees;

SQL> DELETE FROM employees;

SQL> COMMIT;

SQL> UPDATE employeesSQL> UPDATE employees

2> SET salary = salary * 1.5;

SQL> COMMIT;Q ;



Resolution of User Errors

• Train the database users

R f lid b k• Recover from a valid backup

• Import the table from an export file

• Use LogMiner to determine the time of error

• Recover with a point-in-time recovery

• Use LogMiner to perform object-level recovery

• Use FlashBack to view and repair historical data



Causes of Instance Failure

InstanceSGAShared PoolUser Server

Redo LogBuffer

Data Dictionary

LibraryCache

process

Server

DatabaseBuffer Cache

User

processPGA

Data DictionaryCache

DBWRSMONPMON CKPTLGWR Others

processPGA

Java Pool Large Poolprocess

146Control

fil

146Datafile 1

146Redo Log

file 1

Password

files file 1

Parameterfile

146Datafile 2

146

146Redo Log

file 2

file DatabaseDatafile 3



Recovery from Instance Failure

• No special recovery action in needed from DBA• Start the instance• Wait for the “database opened” notification• Notify users• Check the alert log to determine the reason for the failure

SQL> CONNECT / AS sysdbaSQL> CONNECT / AS sysdba

Connected.

SQL> STARTUPQ

...

Database opened.



Causes of Media Failures

• Head crash on a disk drive

Ph i l bl i di f iti t d t b fil• Physical problem in reading from or writing to database files

• File was accidentally erased



Resolutions for Media Failures

• The recovery strategy depends on which backup method was

chosen and which files are affectedchosen and which files are affected

• If available, apply archived redo log files to recover data

itt d i th l t b kcommitted since the last backup



Dumping and Logging

• A dump is a copy of a database that is physically kept away from the database in use (active database)from the database in use (active database).

• A dump is snapshot of a valid database state.

• A log is a journal of the transactions details: ID Operations• A log is a journal of the transactions details: ID, Operations, BFIM (Before Image) and AFIM (After Image) of Data Items, and checkpoint record.p



Checkpoint

• The point of synchronisation between the database and the transaction log file.and the transaction log file.

• All buffers are force-written to secondary storage. • The process is:p

– Suspend execution of transactions temporarily.– Force-write all update operations of committed

transactions from main memory buffers to disk.– Write a [checkpoint] record to the log, and force-write

the log to diskthe log to disk.– Resume executing transactions.



Recovery Techniques

• Deferred Update– A transaction cannot change the database until it reaches its commit– A transaction cannot change the database until it reaches its commit

point. So any transaction cannot read the value of an item that is written by an uncommitted transaction, because items remain locked until a t ti h it it i t H di llb k illtransaction reach its commit point. Hence, no cascading rollback will occur.

– A transaction does not reach its commit point until all its update operations are recorded in the log and the log is force-written to disk (There is no BFIM recorded in log because there is no write to the database buffer)database buffer).

– For the recovery, we redo the committed transactions that started since last checkpoint. Any uncommitted transactions are ignored and restarted (therefore, there is no undo needed).



Example: (Deferred Update Recovery)

[start_transaction, T1][write_item, T1 D, 20][commit T1]

T1[commit, T1][start_transaction, T3][write_item, T3 B, 15][start transaction, T4]

T3

T4[ _ , ][write_item, T4 A, 20][checkpoint][start_transaction T2]

T2

[write_item T2, D, 15][start_transaction, T5][write_item, T5, C, 30][commit T3]

T5

[commit, T3][commit, T2] system crash!

checkpoint t1 system crash

time



Explanations

• Changes on data items A and C performed by T4 and T5 are ignored because the transactions did not reach their commit points.

• T2 and T3 are redone because their commit points are after the last system checkpoint.the last system checkpoint.

• T4 and T5 are restarted.

What would happen for Immediate Update Recovery?Recovery?



Recovery Techniques (con’d)

• Immediate UpdateDatabase buffers are updated immediately after the log is– Database buffers are updated immediately after the log is updated. So the database will be physically updated when the buffers are next flushed to the disk.

– During the recover process, all uncommitted transactions need to be undone, and committed transactions need to be redone.

– Cascading redo and undo transactions are possible during a recovery process.



Recovery Techniques (con’d)

• Shadow PagingDuring the life time of a transaction database buffer pages are– During the life time of a transaction, database buffer pages are maintained by two page tables: current and shadow.

– Shadow page table is never changed and is used for the recovery.p g g y

– When the transaction completes, the current page table becomes the shadow.



Defining a Backup and Recovery Strategy

• Business requirements

O ti l i t• Operational requirements

• Technical considerations

• Management concurrence



Business Requirements

• Mean time to recover– Should be reduced– Anticipating the types of failures that can occur and using effective

recovery strategies• Mean time between failureMean time between failure

– Must be increased– Understand the backup and recovery structures within an Oracle

database environment and configure the database so that failuresdatabase environment and configure the database so that failures do not often occur

• Evolutionary process– Strategy evolves as business, operational, and technical

requirements change



Operational Requirements

• 24-hour operations

P d t b fi ti t t b i ti– Proper database configuration to support business operations

• Testing and validating backups

– A recovery is only a good as the backups that are available

• Database volatility



Technical Considerations

• Resources: hardware, software, manpower, and time

Ph i l i i f th ti t fil• Physical image copies of the operating system files

• Logical copies of the objects in the database

• Database configuration

• Transaction volume that affects desired frequency of backups



Disaster Recovery Issues

• How will your business be affected in the event of a major

disaster such as:disaster, such as:

– Earthquake, flood, or fire

C l t l f hi– Complete loss of machine

– Malfunction of storage hardware or software

Loss of key personnel for example the database administrator– Loss of key personnel, for example the database administrator

• Do you have a plan for testing your strategy periodically?



Oracle Database Backup

• Disk Allocations for an Oracle database• Database Storage Structureg• Logical Backup

– Import/Export utilitiesPh i l B k• Physical Backup– Cold backup– Hot backup



Disk Allocations - Example

• Disk 1: Oracle Software and OSDisk 2: SYSTEM tablespace Control file 1• Disk 2: SYSTEM tablespace, Control file 1

• Disk 3: ROLLBACK SEGMENT tablespace(1& 2), Control File 2( ),

• Disk 4: DATA tablespace, Control file 3• Disk 5: TEMP tablespace• Disk 6: INDEX tablespace

How many tablespaces?tablespaces?



Database Storage Structure

Logical

Database Tablespace Segment Extent Data Block

Physical

Data File O/S Block



Summary

• Evaluate potential failures in your environment

D l t t di t t d b b i ti l d• Develop a strategy dictated by business, operational, and

technical requirements

• Consider a test plan for a backup and recovery strategy



I t d M di R St tInstance and Media Recovery Structures

• Describe the Oracle processes memory structures and filesDescribe the Oracle processes, memory structures, and files relating to recovery

• Identify the importance of checkpoints, redo log files, and archived log filesarchived log files

• Describe ways to tune instance recovery10.01.2010 33Administrarea Bazelor de Date I


Overview

InstanceSGA Shared Pool

Redo LogB ff Data Dictionary

LibraryCache

Server DatabaseB ff C h

Java Pool Large Pool

User Buffer Data DictionaryCache

DBWnSMON PMON CKPT LGWR ARCn

processPGA

Buffer Cacheprocess

146Control

fil

146Datafile 1

146Redo Log

file 1

Password

Parameterfile

files file 1

146Datafile 2

146

146Redo Log

file 2Archivedlog files

file DatabaseDatafile 3



Memory structures

Type Description

Database buffer Memory area used to store blocks read from data files. Data is cache

yread into the blocks by server processes and written out by DBWn asynchronously

Log buffer Memory containing before and after image copies of changed data to be written to the redo logsto be written to the redo logs

Large pool An optional area in the SGA that provides large memory allocations for backup and restore operations, I/O server processes, and session memory for the shared server.y

Shared pool Stores parsed versions of SQL statements, PL/SQL procedures, and data dictionary information

Java pool Used in server memory for all session-specific Java code and dataJava pool Used in server memory for all session specific Java code and data within the JVM



Background Processes

Type Description

Database writer (DBWn) Writes dirty buffers from the data buffer cache to the data files. ( ) yThis activity is asynchronous.

Log writer (LGWR) Writes data from the redo log buffer to the redo log files.

S i (SMON) P f i i R iSystem monitor (SMON) Performs automatic instance recovery. Recovers space in temporary segments when they are no longer in use. Merges contiguous areas of free space depending on parameters that are set.

Process monitor (PMON) Cleans up the connection/server process dedicated to an abnormally terminated user process. Performs rollback and releases the resources held by the failed process.

Checkpoint (CKPT) Synchronizes the headers of the data files and control files withCheckpoint (CKPT) Synchronizes the headers of the data files and control files with the current redo log and checkpoint numbers.

Archiver (ARCn) (optional)

A process that automatically copies redo logs that have been marked for archiving.



Large Pool

• Can be configured as a separate memory area in the SGA to be used for:– Oracle backup and restore operations– I/O server processes– Session memory for the shared serversSession memory for the shared servers

• Is sized by the LARGE_POOL_SIZE parameter

SQL> SELECT * f $ t tSQL> SELECT * from v$sgastat

2> WHERE pool = ‘large pool’;

POOL NAME BYTESPOOL NAME BYTES

------------ --------------- --------

large pool free memory 4194304large pool free memory 4194304



Database Buffer Cache, DBWn, and Data files

InstanceSGASGA

Redo Log

Shared Pool

LibraryCache

Database


Redo LogBuffer Data Dictionary

Cache

DBW0SMON PMON CKPT LGWR ARCn

Serverprocess

PGA

DatabaseBuffer CacheUser

process

0 C

146C t l

146D t fil 1

146Redo Log

DBW1

Parameterfile

Control files

Datafile 1 Redo Log file 1

146Datafile 2

146

146Redo Log


Passwordfile Database

146Datafile 3



Redo Log Buffer, LGWR, and Redo Log Files


LibraryCache



Cache

DBWSMON PMON CKPT LGWR

Serverprocess

PGA

DatabaseBuffer CacheUser

process


146146 146

DBW1

Parameterfile

146Control

files

146Datafile 1 Redo Log

file 1

146Datafile 2

146Redo Log

fil 2Archivedlog files


146Datafile 3

file 2 log files



Multiplexed Redo Log Files

Group 1 Group 2 Group 3

log1a.rdo log1a.rdo log1a.rdo

p p p

Disk 1(Member a) log1a.rdo log1a.rdo log1a.rdo(Member a)

log1b.rdo log1b.rdo log1b.rdoDisk 2

(Member b)

10.01.2010 Administrarea Bazelor de Date I 40


How to relocate a Redo Log file• If the log file is current, perform a log switch by using:

SQL ALTER SYSTEM SWITCH LOGFILE

• Copy the redo log file to the new location

SQL> ALTER SYSTEM SWITCH LOGFILE;

• Use the ALTER DATABASE RENAME FILE to make the change in the control files:

ALTER DATABASE [database]ALTER DATABASE [database]

RENAME FILE ‘filename’[,’filename’]...

TO ‘filename’[ ’filename’]TO filename [, filename ]...



Database Checkpoints

• Checkpoints are used to determine where recovery should start

• Checkpoint position

– where recovery starts

– all the referenced data blocks prior to that point have already been

written to disk by DBWn

• Checkpoint queue – link list of dirty blocks



Types of Checkpoints• Full checkpoint

– All dirty buffers are writtenAll dirty buffers are written

– SHUTDOWN NORMAL, IMMEDIATE, or TRANSACTIONAL

– ALTER SYSTEM CHECKPOINT

• Incremental checkpoint (Fast-Start checkpoint)– Periodic writes

– Only write the oldest blocks

• Partial checkpoint – Dirty buffers belonging to the tablespace

– ALTER TABLESPACE BEGIN BACKUP

ALTER TABLESPACE t bl OFFLINE NORMAL– ALTER TABLESPACE tablespace OFFLINE NORMAL



CKPT Process


Redo Log

Shared Pool

LibraryCache

Server Database


User gBuffer Data Dictionary

Cache


Serverprocess

PGA

Buffer CacheUserprocess

146Control

146Datafile 1

146Redo Log

fil 1

DBW1

Password

Parameterfile

Control files

Datafile 1 gfile 1

146Datafile 2

146

146Redo Log




146Datafile 3


Multiplexed Control Files


Redo Log

Shared Pool

LibraryCache

Server Database


User gBuffer Data Dictionary

Cache


Serverprocess

PGA

Buffer CacheUserprocess

146Datafile 1

146Redo Log

fil 1

DBW1

Control files

Password

Parameterfile

Datafile 1 gfile 1

146Datafile 2

146

146Redo Log


Control files



146Datafile 3


How to Multiplex the Control File

1. Shut down the database

2. Make a copy of the existing control file to a different device

3. Edit or add the CONTROL_FILES parameter and specify

names for all the control files

4. Start the database



ARCn Process and Archived Log FilesInstance

SGA Shared Pool


LibraryCache

Server DatabaseBuffer Cache


User Buffer yCache


processPGA

Buffer Cacheprocess

DBW1ARC1

146Control

files

146Datafile 1

146Redo Log

file 1

DBW1

Archivedl fil

Password

Parameterfile

files146

Datafile 2146

D t fil 3

146Redo Log

file 2 Archivedlog files

log filesdest 2


file DatabaseDatafile 3g

dest 1


Database Synchronization

• All datafiles (except offline and read-only) must be

h i d f th d t b tsynchronized for the database to open

• Synchronization is based on the current checkpoint number

• Applying changes recorded in the redo log files synchronizes

datafiles

• Redo log files are automatically requested by the Oracle server



Phases for Instance Recovery1. Datafiles out-of-synch2. Roll forward (redo)3. Committed and non-


J P l L P lcommitted data in files4. Roll back (undo)5. Committed data in files Redo Log

Buffer Data DictionaryC h

LibraryCache

DatabaseBuffer Cache


Cache

DBW0SMON PMON CKPT LGWR ARCnServer

processPGA

SQL*Plus

146.5Control

146.5Datafile 1

146.5Redo Log

file 1 CheckpointControl files

Datafile 1 file 1

146.5Datafile 2

146.5

145Redo Log

file 2

Checkpoint

Undo

10.01.2010 Administrarea Bazelor de Date I 4910.01.2010 Administrarea Bazelor de Date I 49

DatabaseDatafile 3


Tuning Crash and Instance Recovery g yPerformance

• Tuning the duration of instance and crash recovery

• Tuning the phases of instance recoveryg p y



Tuning the Duration of Instance and Crash RecoveryCrash Recovery

Methods to keep the duration of instance and crash recovery within user-specific bounds:

• Set initialization parameters to influence the number of redo log

records and data blocks involved in recovery

• Size the redo log file to influence checkpointing frequency

• Issue SQL statements to initiate checkpoints

• Parallelize instance recovery operations• Parallelize instance recovery operations



Initialization Parameters Influencing CheckpointingCheckpointing

Parameter DefinitionParameter Definition

FAST_START_MTTR_TARGET Expected MTTR specified in seconds

LOG CHECKPOINT TIMEOUT Amount of time that has passed since theLOG_CHECKPOINT_TIMEOUT Amount of time that has passed since the

incremental checkpoint at the position where

the last write to the redo log occurred

LOG_CHECKPOINT_INTERVAL Number of redo log file blocks that can exist

between an incremental checkpoint and the

last block written to the redo log



V$INSTANCE_RECOVERY

• Used to monitor the mechanisms that are available to limit

I/Orecovery I/O

• Statistics from this view to calculate which parameter has the

greatest influence on checkpointing



V$INSTANCE_RECOVERY• RECOVERY_ESTIMATED_IOS

– Number of dirty buffers in the buffer cachey• ACTUAL_REDO_BLKS

– Number of redo blocks required for recoveryTARGET REDO BLKS• TARGET_REDO_BLKS– Number of redo blocks that must be processed for recovery

• LOG_FILE_SIZE_REDO_BLKS• LOG_CHKPT_TIMEOUT_REDO_BLKS• LOG_CHKPT_INTERVAL_REDO_BLKS

FAST START IO TARGET REDO BLKS• FAST_START_IO_TARGET_REDO_BLKS• TARGET_MTTR• ESTIMATED MTTR_• CKPT_BLOCK_WRITES



Tuning the Phases of Crash and Instance Recovery

Tuning the roll forward phase• Tuning the roll forward phase

• Tuning the rollback phase



Tuning the Rolling Forward Phase

• Parallel block recovery

• RECOVERY_PARALLELISM specifies the number of

concurrent recovery processes



Tuning the Rolling Back Phase

• Fast-start on-demand rollback

– Feature that allows new transactions to begin immediately after

the roll forward phase of recovery completes

• Fast-start parallel rollback



Fast-Start On-Demand Rollback

Server process encountering data to be rolled back performs the

f ll ifollowing:

• Rolls back the block containing the required row

• Hands off further recovery, which may be in parallel, to SMON

I dI dresponseImproved response



Fast-Start Parallel Rollback

SMON

P000P000

P001

UndoP002

Undosegment Tables



Controlling Fast-Start Parallel RollbackControlling Fast Start Parallel Rollback

FAST START PARALLEL ROLLBACK t• FAST_START_PARALLEL_ROLLBACK parameter

Value Maximum Parallel Recovery Serversa ue a u a a e eco e y Se e s

FALSE NoneLOW (default) 2 * CPU COUNTO (de au t) C U_COUHIGH 4 * CPU_COUNT



Monitoring Parallel Rollback

• V$FAST_START_SERVERS

– Provides information about all the recovery slaves performing

parallel transaction recovery

• V$FAST_START_TRANSACTIONS

– Contains information about the progress of the transactions that

Oracle is recovering



Monitoring Parallel Rollbackg• To monitor the use of parallel query slaves for fast-start parallel

rollback:

SELECT * FROM v$fast_start_servers;

STATE UNDOBLOCKSDONE PIDSTATE UNDOBLOCKSDONE PID

----------- --------------- ----

RECOVERING 99 10RECOVERING 99 10

IDLE 0 11

IDLE 0 12

IDLE 0 13



Summary• Identify components of the instance and database that are

significant to recovery• Tune crash and instance recovery



Configuring the Database Archiving ModeConfiguring the Database Archiving Mode

• Describe the differences between ARCHIVELOG and NOARCHIVELOG modes• Configure a database for ARCHIVELOG modeg• Enable automatic archiving• Perform manual archiving of logs• Configure multiple archive processes• Configure multiple destinations, including remote destinations


Redo Log History

N d hi tLGWR 052

No redo history

054 05305 053

051

052

Redo history

Online red log files052



NOARCHIVELOG Mode

• Default when the database is created

• Characteristics:

– Redo log files are used in a circular fashion

– A redo log file can be reused immediately after a checkpoint has

taken place

– After redo logs are overwritten, media recovery is only possible to

the last full backup



NOARCHIVELOG Mode

LGWR

No redohistory

052054

053Online redolog files 052

052054

053



NOARCHIVELOG Mode• Implications of NOARCHIVELOG Mode:

– If a tablespace becomes unavailable because of a failure, you p ycannot continue to operate the database until the tablespace has been dropped or the entire database has been restored from backups

– You can perform operating system backups of the database only when the database is shut down

– You must back up the entire set of datafiles and control files during each backup

– If the online redo log files have been overwritten, you will lose all data since the last full backup



ARCHIVELOG Mode

LGWRLGWRRedo

history

052054

Online redolog files

051

052051

053

052054

053

Archived log file051053054

g053



ARCHIVELOG Mode

Implications:Th d t b i t t d f l f d t h di f il• The database is protected from loss of data when media failure

occurs

• You can back up the database while it is online

• When a tablespace other that SYSTEM goes offline as a result

of media failure, the remainder of the database remains

available because tablespaces can be recovered while the

database is open



Changing the Archiving Mode

SHUTDOWN NORMAL/IMMEDIATE/TRANSACTIONAL1

STARTUP MOUNT2 ALTER DATABASE OPEN4

ControlInit.ora Controlfile

ALTER DATABASE ARCHIVELOG 3 Full database backup5



Automatic and Manual Archivingg

• Automatic archiving: LOG_ARCHIVE_START=TRUE

053 053ARC0

• Manual archiving: LOG_ARCHIVE_START=FALSE

053 053

DBA



Specifying Multiple ARCn Processesp y g p

• The dynamic parameter LOG ARCHIVE MAX PROCESSES y p _ _ _

controls the number of archive processes started at instance

startupstartup

• A maximum of ten ARCn processes can be specified

Th b f ARC b h d ith ALTER• The number of ARCn processes can be changed with ALTER

SYSTEM



Stop or Start Additional Archive PProcesses

LOG ARCHIVE MAX PROCESSES = 2

053053ARC1

_ _ _

053

Online redo logsARC2 Archived redo logs

ALTER SYSTEM SET

LOG_ARCHIVE_MAX_PROCESSES = 3;



Enabling Automatic Archiving at I t St tInstance Startup

Archived A hi d l fil

051 Archived

C t

Archived log files

052

053

Current 053

Online redo logs053ARC0

LOG_ARCHIVE_START=TRUELOG_ARCHIVE_MAX_PROCESSES=n



Enabling Automatic Archiving After Instance StartupInstance Startup

1

ALTER SYSTEM ARCHIVE LOG START;

2

051 052

ALTER SYSTEM ARCHIVE LOG START;

051 052

051ARC0Online redo logs 3


05


Steps…

Step Explanation1 Check the status of the ARCn process:p

SQL> ARCHIVE LOG LIST

2 Enable the archiver processes (ARCn):UNIX:SQL ALTER SYSTEM ARCHIVE LOG START SQL> ALTER SYSTEM ARCHIVE LOG START

TO ‘/ORADATA/ARCHIVE1’;Windows:SQL> ALTER SYSTEM ARCHIVELOG START

‘ 04 l E l ’TO ‘c:\u04\Oracle\TEST\log’;

3 The ARCn processes automatically archive log files as they are filled.



Disabling Automatic Archiving

2Initializationparameters

ALTER SYSTEM ARCHIVE LOG STOP;

1p

051 052

ALTER SYSTEM ARCHIVE LOG STOP;

051 052

051ARC0Online redo logs


05

052


Steps…

Step Explanation1 Execute the command to stop the ARCn processes, if ARCnp p ,

processes have been already enabled:SQL> ALTER SYSTEM ARCHIVE LOG STOP;

2 Ensure that automatic archiving is not enabled upon instance t t b tti th i iti li ti tstartup by setting the initialization parameter:

LOG_ARCHIVE_START = FALSE



Manually Archiving Online Redo Log Files

1

ALTER SYSTEM ARCHIVE LOG CURRENT;

051 052 053

051Server

ProcessServer

Process

Online redo logs

0522


0522


Steps…

Step Explanationp p1 Execute the ALTER SYSTEM SQL command:

SQL> ALTER SYSTEM ARCHIVE LOG CURRENT;

2 The server process for the user executing the command performs p g pthe archiving of the online redo log files.



Specifying the Archive Log Destination

• Use LOG_ARCHIVE_DEST_n to specify up to ten archival

d ti tidestinations

• Use LOG_ARCHIVE_FORMAT to include the log sequence

number and thread number as part of the filename



Specifying Multiple ArchiveLog DestinationsLog Destinations

• Use LOG_ARCHIVE_DEST_n to specify up to ten archival

destinations, which can be on a:

– Local disk

– Remote standby database

log_archive_dest_1 = “LOCATION=/archive1”

Log_archive_dest_2 = “SERVICE=standby_db1”

The service name is resolved using local tnsnames.ora file


You must specify the LOCATION parameter for at least one destination


LOG_ARCHIVE_DEST_n Options

• Set archive location as MANDATORY or OPTIONAL

• Define time before retry in case of failures

log archive dest 1 = “LOCATION=/archive/log_archive_dest_1 LOCATION /archive/

MANDATORY REOPEN”

log archive dest 2 = “SERVICE=standby db1g_ _ _ y_

MANDATORY REOPEN=600”

log_archive_dest_3 = “LOCATION=/archive2/

OPTIONAL”



LOG_ARCHIVE_DEST_n Options• MANDATORY

– archiving to this destination must complete successfully before an g p yonline redo log file can be overwritten

• OPTIONAL– Implies that an online redo log file can be reused even if it has notImplies that an online redo log file can be reused, even if it has not

been successfully archived to this destination (default)• REOPEN

D t i d h th hi i t d ti ti t b– Determined whether archiving to a destination must be reattempted in case of failure

– Number specified (in seconds) for how long to attempt retrying– Without reopen a failure is reported and no further attempts are

made



Specifying a Minimum Numberof Local Destinationsof Local Destinations

• LOG_ARCHIVE_MIN_SUCCEED_DEST parameter

LOG_ARCHIVE_MIN_SUCCEED_DEST = 2

• An online redo log group can be reused only if:

A hi i h b d t ll d t l ti– Archiving has been done to all mandatory locations

– The number of local locations archived is greater than or equal to

th l f th LOG ARCHIVE MIN SUCCEED DESTthe value of the LOG_ARCHIVE_MIN_SUCCEED_DEST

parameter



Controlling Archiving to a Destination• An archival destination can be disabled by using the dynamic

initialization parameter LOG_ARCHIVE_DEST_STATE_n

LOG_ARCHIVE_DEST_STATE_2 = DEFER

ALTER SYSTEM SET log_archive_dest_state_3 =

DEFER;

• Archiving to a destination can be enabled again

LOG_ARCHIVE_DEST_STATE_2 = ENABLE

ALTER SYSTEM SET log_archive_dest_state_3 =

ENABLE


ENABLE


Specifying the Filename FormatOnline redo logs

Group 1 Group 2

051 051Archived log file

052

ARC0 053

052

/ORADATA/archive/arch%s.arc

LOG_ARCHIVE_DEST_n


LOG_ARCHIVE_FORMAT


Obtaining Archive Log Information

• Dynamic views:

• V$ARCHIVED_LOG• V$ARCHIVE DEST• V$ARCHIVE_DEST• V$LOG_HISTORY• V$DATABASE• V$ARCHIVE_PROCESSES

C d Li• Command Line:

ARCHIVE LOG LIST



Example…• All archive log destinations, the current value, mode, and

status:

SELECT destination, binding, target, status

FROM v$archive dest;$ _ ;

DESTINATION BINDING TARGET STATUS

--------------------- --------- -------- --------

/db1/ l /DEMO/ h MANDATORY PRIMARY VALID/db1/oracle/DEMO/arch MANDATORY PRIMARY VALID

/db2/oracle/DEMO/arch OPTIONAL PRIMARY DEFERRED

standbyDEMO OPTIONAL STANDBY ERROR

OPTIONAL PRIMARY INACTIVE

OPTIONAL PRIMARY INACTIVE



Summary

• Configure a database for ARCHIVELOG mode

• Enable automatic archiving

• Perform manual archiving of logs

• Configure multiple archive processes

• Configure multiple destinationsConfigure multiple destinations



Oracle Recovery Manager

• Identify the features and components of RMAN• Describe the RMAN repository and control file usage• Describe channel allocation• Describe the Media Management Library interfaceg y• Connect to RMAN without the recovery catalog• Configure the RMAN environment



Recovery Manager Featuresy g

• RMAN provides a flexible way to:

– Back up the database, tablespaces, datafiles, control files, and

archive logs

– Store frequently executed backup and recovery operations

– Perform incremental block-level backup

– Skip unused blocks

– Specify limits for backupsp y p



Recovery Manager Featuresy g

• RMAN provides a flexible way to:

– Detect corrupted blocks during backup

– Increase performance through:

• Automatic parallelization

• Generation of less redo

• Restricting I/O for backups

• Tape streaming

M b k d t k– Manage backup and recovery tasks



Recovery Manager Components

Server

Targetdatabase Recovery

Manager

Session(polling) Enterprise

Manager

g(RMAN)

ServerSession(rcvcat)

ServerSession

(channel)

ServerSession

(channel) ServerSession

ServerSession

(channel)

( )

MML (default)

Recoverycatalog DB

Disk Disk

MML


Disk Disk


RMAN Repository: Using the Control File

• RMAN repository is metadata about target database and

b k d tibackup and recovery operations

• RMAN repository is always stored in the control file of the

target database

• CONTROL_FILE_RECORD_KEEP_TIME determines the

minimum age in days of a record before it can be overwritten

• The control file can grow in sizeg



Channel Allocation

Di k

S

Disk

ServerSession

ServerSession

Targetdatabase

Channel (sbt)

Channel (disk)RMAN

Session Channel (sbt)



Automatic Channel Allocation• Change the default device type:

RMAN> CONFIGURE DEFAULT DEVICE TYPE TO bt

• Configure parallelism for automatic channels:

RMAN> CONFIGURE DEFAULT DEVICE TYPE TO sbt;

• Configure automatic channel options:

RMAN> CONFIGURE DEFAULT TYPE DISK PARALLELISM 3;

Configure automatic channel options:

RMAN> CONFIGURE CHANNEL DEVICE TYPE DISK

2> FORMAT = ‘/BACKUP/RMAN/%U’;2> FORMAT /BACKUP/RMAN/%U ;

RMAN> CONFIGURE CHANNEL DEVICE TYPE DISK

2> MAXPIECESIZE 2G;


2> MAXPIECESIZE 2G;


Manual Channel Allocation

• BACKUP, COPY, RESTORE, and RECOVER commands require at least one channelrequire at least one channel.

• Allocating a channel starts a server process on the target database.

• Channels affect the degree of parallelism.• Channels write to different media types.• Channels can be used to impose limitsChannels can be used to impose limits.

RMAN> RUN {

2> ALLOCATE CHANNEL 1 TYPE di k2> ALLOCATE CHANNEL c1 TYPE disk

3> FORMAT = ‘/db01/BACKUP/usr0520.bak’;

4> BACKUP DATAFILE ‘/db01/ORADATA/users01.dbf’



Media Management

Recovery Oracle server Media managementgManager session ylibrary

Media managementserver software

Tape library org psingle tape



Types of Connections with RMAN

• Target database

• Recovery catalog database

• Auxiliary database

– Standby database

– Duplicate database

– TSPITR instance (tablespace point-in-time recovery)



Connecting Without a Recovery CatalogTarget

database

Serverprocess(polling)

Serverprocess(default)

Recoverymanager(RMAN)

• Starting RMAN locally

UNIX: $ ORACLE_SID=DB01; export ORACLE_SID

$ t t / db

• Starting RMAN locally

$ rman target / as sysdba

Windows NT: c:\> set ORACLE_SID=DB01

c:\> rman target / as sysdba

• Starting RMAN remotely

/


rman target sys/target_pwd@DB01


Additional RMAN CommandLi A tLine Arguments

• Writing RMAN output to a log file:Writing RMAN output to a log file:

$ rman target sys/oracle

log $HOME/ORADATA/u03/rman.log append

• Executing a command file when RMAN is invoked:

g g pp

$ rman target sys/oracle

log $HOME/ORADATA/u03/rman.log append

@’$HOME/STUDENT/LABS/my rman script rcv’@ $HOME/STUDENT/LABS/my_rman_script.rcv



Recovery Manager Modes

• Interactive mode

– Use it when doing analysis

– Minimize regular usage

– Avoid using with log option

• Batch mode

– Meant for automated jobs

– Minimize operator errors

– Set the log file to obtain information



RMAN Commands

RMAN commands are of the following types:CHANGE

• Stand-alone

– Executed only at the RMAN prompt

CONNECTCREATE CATALOGRESYNC CATALOG

CREATE SCRIPTDELETE SCRIPT

– Executed individually

– Cannot appear as subcommands within RUN

DELETE SCRIPTREPLACE SCRIPT

• Job

– Must be within the brackets of RUN

– Executed as a group



Job Command: Example

RUN command:RUN command:

RMAN> RUN {

backupp

incremental level 0

format ‘/u01/db01/backup/%d_%s_%p’

fil t 5fileperset 5

(database include current controlfile);

sql ‘alter database archive log current’;

}



RMAN Configuration Settings

• RMAN is preset with default configuration settings

• Use the CONFIGURE command to:

– Configure automatic channels

– Specify the backup retention policy

– Specify the number of backup copies to be created

– Limit the size of backup sets

– Exempt a tablespace from backup

– Enable and disable backup optimization



The CONFIGURE Command

RMAN> CONFIGURE CHANNEL DEVICE TYPE DISK FORMAT

• Configure automatic channels:

RMAN> CONFIGURE CHANNEL DEVICE TYPE DISK FORMAT

‘/db01/BACKUP/%U’;

RMAN> CONFIGURE RETENTION POLICY TO RECOVERY

2> WINDOW OF 7 DAYS;

• Implement retention policy by specifying a recovery window:

2> WINDOW OF 7 DAYS;

• Implement retention policy by specifying redundancy:

RMAN> CONFIGURE RETENTION POLICY TO REDUNDANCY 2;



The CONFIGURE Command• Configure duplexed backup sets:

RMAN> CONFIGURE DATAFILE BACKUP COPIES FORRMAN> CONFIGURE DATAFILE BACKUP COPIES FOR

2> DEVICE TYPE disk TO 2;

• Configure backup optimization:

RMAN> CONFIGURE BACKUP OPTIMIZATION ON;

• Use the CLEAR option to return to the default:

RMAN> CONFIGURE RETENTION POLICY CLEAR;RMAN> CONFIGURE RETENTION POLICY CLEAR;

RMAN> CONFIGURE CHANNEL DEVICE TYPE sbt CLEAR;



The SHOW CommandThe SHOW Command

• Displays a persistent configuration settingsp y p g g• Use the SHOW command to display:

– Automatic channel configuration settingsBackup retention policy settings

SHOW CHANNEL

SHOW DEVICE TYPE– Backup retention policy settings– Number of backup copies to be created– Backup set size limit

SHOW DEVICE TYPE

SHOW RETENTION POLICY– Tablespace excluded fro backups– Backup optimization status

• Use SHOW ALL to display all settings:Use SHOW ALL to display all settings:

RMAN> SHOW ALL;



LIST Command Operations

• Lists backup sets and copies of datafiles

• Lists backup sets and copies of any datafile for a specified

tablespace

• Lists backup sets and copies containing archive logs for a

specified range



The LIST Command• List backups of all files in the database

RMAN> LIST BACKUP OF DATABASE

• List all backup sets containing the users01.dbf datafile:

RMAN> LIST BACKUP OF DATABASE;

•RMAN> LIST BACKUP OF DATAFILE

2> “/db01/ORADATA/u03/users01.dbf”;

• List all copies of datafiles in the SYSTEM

RMAN> LIST COPY OF TABLESPACE “SYSTEM”;



The REPORT Command

• Produces a detailed analysis of the repository

• Produces reports to answer:

– Which files need a backup?

– Which backups can be deleted?

– Which files are unrecoverable?



RMAN Usage Considerations

• Resources: Shared memory, more processes

• Privileges given to users:

– Database: SYSDBA

– Operating System: Access to devices

• Remote operations

– Set up the password file

– Ensure that the password file is backed upp p

• Globalization environment variables

• Format used for the time parameters in RMAN commands• Format used for the time parameters in RMAN commands



Summary

• Configure the RMAN environment

• Use automatic channel allocation

• Manually allocate channels

• Connect to RMAN without the recovery catalog

• Retrieve information from the RMAN repositoryRetrieve information from the RMAN repository


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