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Lesson 5 Recovering a NOARCHIVELOG database
Objective Perform a NOARCHIVELOG database recovery.

Recovering NOARCHIVELOG Database

Suppose you have a database running in NOARCHIVELOG mode. Disk 1 is damaged due to a media failure, and datafile #1 on this disk is lost. There are two online log files containing sequence numbers 75 and 76, with the current log sequence 76. The most recent backup was made at log sequence 73. Is it possible to completely recover this database? No.

Damaged Data files along with the available backup files

Explanation

If the DBA replaces datafile #1 with a backup copy made at log sequence 73, it cannot be made current with the rest of the database, which is currently at 76. There are not enough logs available.
Online redo logs are not being archived. The current two logs, 75 and 76, at one time held sequence number 73. But each log is over-written at every log switch. Since the redo log 73 was over-written, a whole database restore is necessary. Remember, if a database is running in NOARCHIVELOG mode, you have to restore the whole database backup even though only one file has been corrupted or lost.


Steps for recovery

Click the Simulation button to see how to perform a NOARCHIVELOG database recovery.
You may also preview all steps.
No Archive Log Recovery Steps
The following code shows what you would see on your screen when you perform a NOARCHIVELOG database recovery.
SVRMGR>
SVRMGR> CONNECT INTERNAL
Password:
Connected.
SVRMGR> SHUTDOWN ABORT
ORACLE instance shut down.
SVRMGR> HOST
Microsoft(R) Windows NT(TM)
(C) Copyright 1985-1996 Microsoft Corp.

C:\> COPY C:\DIGITAL\BACKUP\*.* C:\ORANT\DATABASE\
C:\digital\backup\Usr1orcl.ora
C:\digital\backup\Rbs1orcl.ora
C:\digital\backup\Tmp1orcl.ora
C:\digital\backup\Sys1orcl.ora
C:\digital\backup\Oem1orcl.ora
C:\digital\backup\Ctl1orcl.ora
C:\digital\backup\Log1orcl.ora
C:\digital\backup\Log2orcl.ora
C:\digital\backup\Log3orcl.ora
C:\digital\backup\Log4orcl.ora
C:\digital\backup\Initorcl.ora
 11 file(s) copied.
 
C:\>EXIT
SVRMGR> STARTUP OPEN PFILE=C:\ORANT\DATABASE\INTIORCL.ORA
ORACLE instance started.
Total System Global Area                         15077376 bytes
Fixed Size                                          49152 bytes
Variable Size                                    12906496 bytes
Database Buffers                                  2048000 bytes
Redo Buffers                                        73728 bytes
Database mounted.
Database opened.
SVRMGR>

The next lesson explains how to restore files to a different location after a media failure.

Recovering Noarchivelog Database - Quiz

Click the Quiz link below to review your understanding of recovering a NOARCHIVELOG database.
Recovering Noarchivelog Database - Quiz