BACKUP,RESTORE AND RECOVERY:
--------------------------------------------
--> BACKUP TYPES
1) PHYSICAL BACKUP
2) LOGICAL BACKUP
1) PHYSICAL BACKUP:
----------------------------
--> BACKUP OF DATAFILES ,CONTROL FILES AND REDOLOG FILES
COMPLETE BACKUP --> IF U TAKE ALL AS BACKP
PARTIAL BACKUP --> IF U TAKE NOT ALL AS BACKUP
--> TYPES OF PHYSICAL BACKUP
COLD BACKUP --> TAKING BACKUP WHEN DATABASE IS IN SHUTDOWN
HOT BACKUP --> TAKING BACKUP WHEN DATABASE IS RUNNING
(IN THIS WE CANT TAKE BACKUP THE CONTROL AND REDOLOG FILES)
--> RMAN IS A TOOL FOR THE PHYSICAL BACKUP
FOR RMAN --> RECOVERY_CATLOG_OWNER
--> INCREMENTAL BACKUPS
2) LOGICAL BACKUP :
---------------------------
--> TAKING BACKUP THE DEFINITIONS AND IT'S DATA ALSO
-->IN THIS WE TAKE
--> ONLY SCHEMA
--> SCHEMA + DATA
--> LEVELS IN THIS
--> DATABASE LEVEL
--> TABLESPACE LEVEL
--> USER LEVEL
--> TABLE LEVEL
--> PUT IN A DUM FILE
--> TAKES LESS SIZE WHEN COMPARED TO PHYSICAL BACKUP
--> IT TAKES MORE TIME THAN THE PHYSICAL BACKUP
--> INCREMENTAL BACKUPS ( ONLY TAKING CHAGES AFTER THE LAST BACKUP)
--> CUMULATIVE BACKUPS ( TAKING ALL INCREMENTAL BACKUPS)
--> FULL BACKUP
--> UTILITIES FOR LOGICAL BACKUP( CLIENT TOOLS)
--> EXP (FOR LOGICAL BACKUPS)
--> IMP (FOR LOGICAL BACKUP RESTORE)
--> FOR DATABASE BACKUP(EXP AND IMP)
EXP_FULL_DATABASE --> ROLE FOR TAKING FULL DATABASE BACKUP
IMP_FULL_DATABASE --> ROLE FOR RESTORE THE DATABASE
--> 10G ONWARDS
--> EXPDP
--> IMPDP
backing up database:
--------------------
--> As an oracle DBA,one of your fundamental tasks is regularly backup databases
--> no backup, no recovery
--> backups are
-- physical backups
-- backing up of the key oacle database files:datafiles
-- logical backups
-- taking backup of definition and data also
--> the physical backups can perform in two ways
-- user managed backups
-- in this we use os commands cp and sql commands
-- RMAN backups
-- used in command line and OEM databse control interface
--> backups are
-- whole and partial backups
-- taking all as backup is whole backup
-- taking some as backup is partial backup
-- consistent and inconsistent backups
-- a consistent backup doesnot need to go through recovery process
-- an inconsistent backup alwys needs to undergo a recovery
-- open and closed backups
-- online or open(hot backup) backups are you make while the database is open and accessible to
users
-- a closed backup(cold backup) is made while the datbase is shutdown.its always consistent.
--> bakcup levels
-- whole database
-- tablespace backups
-- datafile backups
--> flash recovery area as the default area for storing every file related to backup and restore operations
--> parameter to set the flash recover area size
-- db_recovery_file_dest_size
sql> alter system set db_recovery_file_dest=2G;
database recovery:
------------------
--> types of failures
-- system failures
-- data center disasters
-- human errors
-- media failures
--> recoveries are
-- complete recovery
-- incomplete recovery
-- time based recovery
-- change based scn
-- log sequence based recovery
--> typical media recovery scenarios
-- complete recovery of a whole database
-- recovering a tablespace
-- recovering datafile
-- incomplete recovery
-- recovering from the loss of control file
-- recovering a datafile without a backup
user managed backups:
---------------------
--> in user managed backups,you can take backup by using os copy commands such as cp and dd in unix, and the copy command in windows systems
--> if the database is in archive mode then we can take open batabase backup
--> if the database is in noarchive mode then we can take closed database backup
--> for backup we use sql command
-- begin backup and end backup
--> the possible backups are
-- whole open backup
--partial database backups
--> whole open backup
sql> alter database begin backup;
sql> host cp /u01/app/oracle/oradata/orcl/*.dbf /u01/app/oracle/bck
sql> alter database end backup;
--> partial database backups
sql> alter tablespace users begin backup;
sql> host cp /u01/app/oracle/oradata/orcl/users01.dbf /u01/app/oracle/bck
sql> alter tablespace end backup;
--> views for monitoring backups
v$backup -- determining whether any of the datafiles are still in backup mode
v$datafiles -- about datafiles
v$log -- about online redologs
v$archivelog -- about archive log information
v$log_history -- redologs that have been archived
sql> desc v$backup
Name Null? Type
------------------ -------- ----------------------------
FILE# NUMBER
STATUS VARCHAR2(18)
CHANGE# NUMBER
TIME DATE
--> typical media recovery scenarios
-- complete recovery of a whole database
-- restore the datafiles from backup
-- start the database in mount state
sql> startup mount;
-- recove the database
sql> recover automatic database
-- open the database
sql> alter database open
-- recovering a tablespace
-- offline tablespace
sql> alter tablesapce users offline immediate;
-- restore the damaged file
sql> host cp /u01/orcl/users01.dbf /uo1/bck/user01.dbf;
-- recover the tablespace
sql> recover tablespace users;
-- online the tablespace
sql> alter tablsepace users online;
-- recovering datafile
-- offline tablespace
sql> alter tablesapce users offline immediate;
-- restore the damaged file
sql> host cp /u01/orcl/users01.dbf /uo1/bck/user01.dbf;
-- recover the tablespace
sql> recover tablespace users;
-- online the tablespace
sql> alter tablsepace users online;
-- incomplete recovery
-- shutdown the database
sql> shutdown immediate;
-- restore all the datafile and make sure that all of them are online
-- choose the recovery option
-- cancel based recovery
sql> recover database until cancel;
-- time based recovery
sql> recover database until time '2012-03-30:12:00:00';
sql> recover database until time '2012-03-30:12:00:00'
using backup controlfile;
-- change based recovery
sql> recover database until change 27845;
-- open the database with resetlogs option
sql> alter database open resetlogs;
-- recovering from the loss of control file
-- recovering a datafile without a backup
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