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Saturday, August 30, 2014

Recovery Manager (Data Recovery Advisor)

  One of the great new features of RMAN in Oracle 11g is the new tool named Data Recovery  Advisor. This tool automates the diagnose of the data failure and corruption, advises the recovery steps and performs automatic recovery of the database failure.  This tool could be used from GUI as well as from CLI.

  The Data Recovery Advisor automatically diagnoses corruption or loss of persistent data on disk, determines the appropriate repair options, and executes repairs at the user's request. This reduces the complexity of recovery process, thereby reducing the Mean Time To Recover (MTTR).
            List Failure       # lists the results of previously executed failure assessments. Revalidates   existing failures and closes them, if possible.
          Advise Failure   # presents manual and automatic repair options
           Repair Failure   # automatically fix failures by running optimal repair option, suggested by ADVISE FAILURE. Revalidates existing failures when completed.
           Change Failure # enables you to change the status of failures.

Scenario based explanation

Step:1 Tablespace creation

create tablespace tbs1 datafile '/u01/app/oracle/product/' size 5m;
create tablespace tbs2 datafile '/u01/app/oracle/product/' size 5m;

 Step:2 creating table in the tablespace

create table tab1 tablespace tbs4 as select * from scott.emp;
create table tab2 tablespace tbs5 as select * from scott.emp;
alter system switch logfile;

 Step:3 checking block in the tablespace

select segment_name , header_file , header_block     
from dba_segments

where segment_name = 'TAB1';
Step:4 taking backup using rman

backup database plus archivelog;

Step:5 checking through DBV  tool

cd $ORACLE_BASE/oradata/prod
dbv file=tbs1.dbf  blocksize=8192

Step:6 corrupt the datafile

dd of=tbs1.dbf bs=8192 conv=notrunc seek=130 << EOF

Step: 7 once again check using dbv Tool

dbv file=tbs1.dbf  blocksize=8192 

Step:8 remove the datafile in os level

cd $ORACLE_BASE/oradata/prod/

rm tbs2.dbf

Step:9 flush the buffer

alter system flush buffer_cache;

Step:10 We are facing the issue here

select count(*) from tab1;

Step:11 shutdown database

Step:12 startup mount

Step:13 alter database datafile  7 offline;

Step:14 alter database open;

Setp:15 checking the corruption

 select * from v$database_block_corruption;
 select * from V$recover_file;

Step:15 list failure;

Step:16 advise failure all;

Step:17 repair failure preview;

Step:18 repair failure;

Step:19  select * from v$database_block_corruption;

Step:20 select * from tab1 and tab2;


1 comment:

Sridevi K said...

Sridevi Koduru (Senior Oracle Apps Trainer
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Please Contact for One to One Online Training on Oracle Apps Technical, Financials, SCM, SQL, PL/SQL, D2K at | +91 - 9581017828.