BACKUP AND RECOVERY

BACKUP AND RECOVERY

Media Failure and Recovery:

Database in NOARCHIVELOG Mode

Failure : loss of disk,data file,or corruption

Recovery : Restore all Oracle files:

- Data files

- Control files

- Redo log files

- Password file (optional)

- Parameter file (optional)

Advantage

·         Easy to perform with low risk of error

·         Recovery time is the time it takes to restore all files.

Disadvantage

·         Data is lost and must be reapplied manually

·         The entire database is restored to the point of the last whole closed backup

Recovery

            > shutdown

Restore all files using operating system

            > startup

Restoring to a Different Location

            > startup mount

            > alter database rename file ’/clover/oradata/user_01.dbf’ to                                                                                                ’/clover/oradata/user_01.dbf’;

            > alter database open;

Media Failure and Recovery:

ARCHIVELOG Mode

Failure : loss of disk,data file,or corruption

Recovery

- Data files for restore must be offline.

- Restore only lost or damaged data files

- Do not restore the control files, redo log files, password files, or parameter files

- Recover the data files.

Advantages

·         Only need to restore lost files

·         Recovers all data to the time of failure

·         Recovery time is the time it takes to restore lost files and apply all archived log files

Disadvantages

·         Must have all archived log files since the backup from which you are restoring

Complete recovery

·         Closed database recovery for

- System data files

- Rollback segment data files

- Whole database

·         Opened database recovery, with database initially opened : for file loss

·         Opened database recovery with database initially closed : for hardware failure

·         Data file recovery with no data file backup

Incomplete recovery

·         Time based

·         Cancel based

·         Using control file

·         Change based

Closed database backup

No archive log mode

Data files, Control files, Redolog files, Parameter file, Password file

            > SHUTDOWN IMMEDIATE

            cp  /backup

            > STARTUP OPEN;

Open database backup

Archive log mode

Data files, Control files, Parameter file, Password file

Arch process must be enabled

            > alter tablespace TEST begin backup;

            cp /clover/data/test.dbf  /clover/backup/test.dbf

            > alter tablespace TEST end backup;

Creating a binary image;

            > alter database backup controlfile to ‘controll.bk

Creating a text trace file:       

            > alter database backup controlfile to trace;