RMAN Recovery Documentation


Benefits of RMAN
1. RMAN is basically a system by which we can recover out database up to point in time. Till now we have IMP, EXP backup utility by which we were taking our backups. Which
Have some disadvantages. Let we have taken our data backup at 10 a.m. by using IMP utility and my database get corrupt at 5 p.m. we can restore is from the 10 a.m. backup but after restoring the data available up to 10 a.m. only i.e. the transaction between 10 a.m. to 5 p.m. are lost. This is not affordable in case of financial transactions.
To overcome this problem we use RMAN. By using RMAN we can recover our database up to the time.
Some technical requirements for RMAN
1. To configure RMAN database must be in archive log mode. By default which is in non archive mode.
2. Flash_recover_area must have enough space to store archive log files.
Steps to recover database using RMAN
1. Whenever any datafile get corrupt you will get message like.
SQL> select count(*) from lost_table;
select count(*) from lost_table
*
ERROR at line 1:
ORA-01116: error in opening database file 6
ORA-01110: data file 6: '/ra5a/orabkp/test/TEST/datafile/lost.dbf'
ORA-27041: unable to open file
Linux-x86_64 Error: 2: No such file or directory
Additional information: 3
This shows our lost.dbf data file is corrupt. Now we need to recover this data file.
2. Use commands like.
C:\Documents and Settings\umesh>sqlplus sys as sysdba
SQL*Plus: Release 10.2.0.1.0 - Production on Wed Sep 24 06:09:17 2008
Copyright (c) 1982, 2005, Oracle. All rights reserved.
Enter password:
Connected to:
Oracle Database 10g Enterprise Edition Release 10.2.0.1.0 - Production
With the Partitioning, OLAP and Data Mining options
SQL> shutdown immediate;
SQL> startup mount;
3. Now this step is to restore and recover database. We have two ways to do it.
1) Recovery using command prompt.
2) Recovery using Oracle Enterprise manager database control.
We will discuss each one by one.
4. Recovery using command prompt.
Use commands like.
C:\Documents and Settings\umesh>rman target sys
Recovery Manager: Release 10.2.0.1.0 - Production on Wed Sep 24 06:21:27 2008
Copyright (c) 1982, 2005, Oracle. All rights reserved.
target database Password:
connected to target database: TEST (DBID=1962390848, not open)
RMAN>
RMAN> restore database;
(This command will restore data files from backup).
RMAN> recover database;
(This command will recover your database up to the time.)

Thanks
Umesh Sharma

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