Sunday, May 27, 2012

Article About Data Recovery Method

1-  If you lost all data files

SQL> startup mount;
RMAN> restore database;
RMAN> recover database;
SQL> alter database open;
2- If you lost a tablespace

SQL> alter tablespace users offline;
RMAN> restore tablespace users;
RMAN> recover tablespace users;
SQL> alter tablespace users online;
 if you can not offline tablespace;

$ sqlplus “/ as sysdba”
SQL> shutdown abort;
SQL> startup mount;
$ rman target / catalog_user/catalog_user_password@catalogdb
RMAN> restore tablespace users;
RMAN> recover tablespace users;
SQL> alter database open;

3- if you lost a datafile

SQL> alter database datafile '/oracle/oradata/users.dbf' offline;
RMAN> restore datafile '/oracle/oradata/users.dbf'
RMAN> recover datafile '/oracle/oradata/users.dbf'
SQL> alter database datafile '/oracle/oradata/users.dbf' online;
 
if you cannot offline datafile;


$ sqlplus “/ as sysdba”
SQL> shutdown abort;
SQL> startup mount;
$ rman target / catalog_user/catalog_user_password@catalogdb
RMAN> restore datafile '/oracle/oradata/users.dbf';
RMAN> recover datafile '/oracle/oradata/users.dbf';
SQL> alter database open;
 

4-  if you lost your controlfiles

$ sqlplus “/ as sysdba”
SQL> shutdown abort;
SQL> startup nomount;
$ rman target / catalog_user/catalog_user_password@catalogdb
RMAN> set dbid = 3970640872;
RMAN> restore controlfile;
SQL> alter database mount;
SQL> alter database open;
you will receive an error ORA-01589 when you open database
ORA-01589: must use RESETLOGS or NORESETLOGS option for database open

SQL> shutdown abort;
SQL> startup mount;
$ rman target / catalog_user/catalog_user_password@catalogdb
RMAN> recover database;
SQL> alter database open resetlogs;
RMAN> reset database;
if you open database with resetlogs, SCN number will be zero. In this situation
all previous backups will be invalid. You must full backup.


5- May be a special situation. You need to incomplete recovery

A. Time-Based incomplete recovery

$ sqlplus "/ as sysdba"
SQL> shutdown abort;
SQL> startup mount;
$ rman target / catalog_user/catalog_user_password@catalogdb
RMAN> restore database until time "to_date('06/05/11 12:0:00','DD/MM/YY HH24:MI:SS')";
RMAN> recover database until time "to_date('06/05/11 12:0:00','DD/MM/YY HH24:MI:SS')";
SQL> alter database open resetlogs;
 
 
B. SCN-Based incomplete recovery

$ sqlplus "/ as sysdba"
SQL> shutdown abort;
SQL> startup mount;
$ rman target / catalog_user/catalog_user_password@catalogdb
RMAN> restore database until scn 1000;
RMAN> recover database until scn 1000;
SQL> alter database open resetlogs;
C. Archive log sequence based incomplete recovery

$ sqlplus "/ as sysdba"
SQL> shutdown abort;
SQL> startup mount;
$ rman target / catalog_user/catalog_user_password@catalogdb
RMAN> restore database until sequence 9923;
RMAN> recover database until sequence 9923;
SQL> alter database open resetlogs;

6-  if you need some archive logs in your backup

$ rman target / catalog_user/catalog_user_password@catalogdb
RMAN> restore ARCHIVELOG FROM TIME 'SYSDATE-1' UNTIL TIME 'SYSDATE';
 
OR

RMAN> restore ARCHIVELOG FROM TIME "to_date('07/11/05 00:00:01','MM/DD/YY HH24:MI:SS')
UNTIL TIME 'SYSDATE';
 
7- if your data block is corrupted you will receive an error below.

Error:
ORA-01578: ORACLE data block corrupted (file # 8, block # 13)
ORA-01110: data file 8: ‘/oracle/oradata/users.dbf’

for recover data block;

$ rman target / catalog_user/catalog_user_password@catalogdb
RMAN>blockrecover datafile 8 block 13;
 
For Block-Level Media Recovery – Concept & Example (Doc ID 144911.1)

To recover, we can give a specific backup set;

# recovery from backupset
RMAN> BLOCKRECOVER DATAFILE 8 BLOCK 13 DATAFILE 2 BLOCK 19 FROM BACKUPSET;
# recovery from image copy
RMAN> BLOCKRECOVER DATAFILE 8 BLOCK 13 DATAFILE 2 BLOCK 19
      FROM DATAFILECOPY;
# recovery from backupset which have "FULL" tag
RMAN> BLOCKRECOVER DATAFILE 8 BLOCK 13 DATAFILE 2 BLOCK 199
       FROM TAG = FULL;
During backup or “Validate Backup” command, RMAN finds corrupted blocks and writes to V$DATABASE_BLOCK_CORRUPTION view. When the RMAN recover the corrupt block then automatically updates this view. List of all the corruption of the past, can be viewed over V$BACKUP_CORRUPTION and V$COPY_CORRUPTION views.  If you run the following command,  RMAN will recover all the corrupted blocks in view V$DATABASE_BLOCK_CORRUPTION.

  RMAN>BLOCKRECOVER CORRUPTION LIST RESTORE UNTIL TIME 'SYSDATE-10';
8- if you have a image copy backup and your datafile number 2 has problems then you
can switch datafile number2 to image copy.

RMAN>sql ‘alter database datafile 2 offline’;
RMAN>switch datafile 2 to copy;
RMAN>recover datafile 2;
RMAN>sql ‘alter database datafile 2 online’;


Orginial Article
 Thank You
 Osama Mustafa




3 comments:

  1. This comment has been removed by the author.

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  2. Thank you for useful advices. It's a data recovery method, which I have not heard before, but I hope I shouldn't have make use of it:). Recently I've read an article about recovering data from disk after a flood or flooding and now I know what what I shouldn't do with my hard drive.

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  3. Nice Comment , This Give me motivation to continue what i am doing i am sharing my knowledge for something i really Love .

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