Use of DRA (Data Recovery Advisor)

Use of DRA (Data Recovery Advisor)

The official description of DRA:

The simplest way to diagnose and repair database problems is to use the Data Recovery Advisor. This Oracle Database tool provides an infrastructure for diagnosing persistent data failures, presenting repair options to the user, and automatically executing repairs.

Next we will do a small experiment to realize the convenience of DRA:

1. Rman login to the target database
2. Here we simulate the loss of a data file
3. Observe how DRA recovers the database.

1. rman log on to the target database

[oracle@JY-DB BACKUP]$ rman target /Recovery Manager: Release 11.2.0.4.0 - Production on Wed Aug 5 11:15:12 2015Copyright (c) 1982, 2011, Oracle and/or its affiliates.  All rights reserved.connected to target database: JYZHAO (DBID=2463175424, not open)RMAN> LIST FAILURE;using target database control file instead of recovery catalogno failures found that match specification

We can see that no matching item is found in the database.

2. Here we simulate the loss of a data file

#2.1 properly shut down the database SQL> shutdown immediateDatabase closed. database dismounted. ORACLE instance shut down. #2.2 Delete data files + DATA1/jyzhao/datafile/dbs_d_jingyu.259.886871319 # directly Delete the data file will report an error ASMCMD> rm DBS_D_JINGYU.259.886871319ORA-15032: not all alterations performedORA-15028: ASM file '+ DATA1/jyzhao/datafile/DBS_D_JINGYU.259.886871319' not dropped; currently being accessed (dbd error: OCIStmtExecute) # The database is successfully deleted after it is closed. ASMCMD> rm DBS_D_JINGYU.259.886871319ASMCMD> #2.3 An error occurred while trying to open the database. SQL> startupORACLE instance started. total System Global Area 1620115456 bytesFixed Size 2253704 bytesVariable Size 905972856 bytesDatabase Buffers 704643072 bytesRedo Buffers 7245824 bytesDatabase mounted. ORA-01157: cannot identify/lock data file 15-see DBWR trace fileORA-01110: data file 15: '+ DATA1/jyzhao/datafile/dbs_d_jingyu.259.886871319'

3. Observe how DRA restores the database's 3.1 list failure;

RMAN> LIST FAILURE;List of Database Failures=========================Failure ID Priority Status    Time Detected Summary---------- -------- --------- ------------- -------4042       HIGH     OPEN      05-AUG-15     One or more non-system datafiles are missing

3.2 advise failure;

RMAN> ADVISE FAILURE;List of Database Failures=========================Failure ID Priority Status    Time Detected Summary---------- -------- --------- ------------- -------4042       HIGH     OPEN      05-AUG-15     One or more non-system datafiles are missinganalyzing automatic repair options; this may take some timeallocated channel: ORA_DISK_1channel ORA_DISK_1: SID=25 device type=DISKanalyzing automatic repair options completeMandatory Manual Actions========================no manual actions availableOptional Manual Actions=======================1. If file +DATA1/jyzhao/datafile/dbs_d_jingyu.259.886871319 was unintentionally renamed or moved, restore it2. Try flush redo using ALTER SYSTEM FLUSH REDO TO 'standby name' command.  Then perform a Data Guard role change (failover).  Available standbys: jyzhao_s.Automated Repair Options========================Option Repair Description------ ------------------1      Restore and recover datafile 15    Strategy: The repair includes complete media recovery with no data loss  Repair script: /u01/app/oracle/diag/rdbms/jyzhao/jyzhao/hm/reco_4099084102.hm

3.3 repair failure;

RMAN>  REPAIR FAILURE;Strategy: The repair includes complete media recovery with no data lossRepair script: /u01/app/oracle/diag/rdbms/jyzhao/jyzhao/hm/reco_4099084102.hmcontents of repair script:   # restore and recover datafile   restore datafile 15;   recover datafile 15;   sql 'alter database datafile 15 online';Do you really want to execute the above repair (enter YES or NO)? yesexecuting repair scriptStarting restore at 05-AUG-15using channel ORA_DISK_1channel ORA_DISK_1: starting datafile backup set restorechannel ORA_DISK_1: specifying datafile(s) to restore from backup setchannel ORA_DISK_1: restoring datafile 00015 to +DATA1/jyzhao/datafile/dbs_d_jingyu.259.886871319channel ORA_DISK_1: reading from backup piece /u01/app/oracle/product/11.2.0/db_1/dbs/arch/JYZHAO/backupset/2015_08_05/o1_mf_nnndf_TAG20150805T102730_bw2x4m1l_.bkpchannel ORA_DISK_1: piece handle=/u01/app/oracle/product/11.2.0/db_1/dbs/arch/JYZHAO/backupset/2015_08_05/o1_mf_nnndf_TAG20150805T102730_bw2x4m1l_.bkp tag=TAG20150805T102730channel ORA_DISK_1: restored backup piece 1channel ORA_DISK_1: restore complete, elapsed time: 00:00:01Finished restore at 05-AUG-15Starting recover at 05-AUG-15using channel ORA_DISK_1starting media recoverymedia recovery complete, elapsed time: 00:00:00Finished recover at 05-AUG-15sql statement: alter database datafile 15 onlinerepair failure completeDo you want to open the database (enter YES or NO)? yesdatabase openedRMAN> 

At this point, the DRDs instance is automatically restored and the database is successfully opened.