Last modified on 5 April 2013, at 05:56

RAC Attack - Oracle Cluster Database at Home/Flashback Database


  1. Before opening the database, enable flashback database.

    SQL> alter database flashback on;
    Database altered.
     
    SQL> alter database open;
    Database altered.
     
    SQL> select flashback_on from v$database;
     
    FLASHBACK_ON
    ------------------
    YES
     
    SQL> select oldest_flashback_scn,flashback_size from v$flashback_database_log;
     
    OLDEST_FLASHBACK_SCN FLASHBACK_SIZE
    -------------------- --------------
                  610425        8192000
    


  2. Now, login to collabn2 and startup the database from sqlplus. You will get an error message.

    collabn2:/home/oracle[RAC2]$ ss
    SQL*Plus: Release 11.1.0.6.0 - Production on Mon May 4 09:21:25 2009
     
    SQL> startup
    ORACLE instance started.
     
    Total System Global Area  318054400 bytes
    Fixed Size                  1299624 bytes
    Variable Size             142609240 bytes
    Database Buffers          167772160 bytes
    Redo Buffers                6373376 bytes
    Database mounted.
    ORA-38760: This database instance failed to turn on flashback database
     
    SQL> select flashback_on from v$database;
     
    FLASHBACK_ON
    ------------------
    YES
    
    SQL> select oldest_flashback_scn,flashback_size from v$flashback_database_log;
     
    OLDEST_FLASHBACK_SCN FLASHBACK_SIZE
    -------------------- --------------
                       0       16384000
    


  3. Interestingly, the database seems to be running alright. Investigate the alert log for error messages.

    collabn2:/home/oracle[RAC2]$ cdd
    collabn2:/u01/app/oracle/diag[RAC2]$ cd rdbms/rac/RAC2/trace/
    collabn2:/u01/app/oracle/diag/rdbms/rac/RAC2/trace[RAC2]$ less alert_RAC2.log
     
    Mon May 04 09:22:07 2009
    Errors in file /u01/app/oracle/diag/rdbms/rac/RAC2/trace/RAC2_ora_22856.trc:
    ORA-38701: Flashback database log 1 seq 1 thread 1: "/u01/app/oradata/RAC/flashb
    ack/o1_mf_4zxxs99n_.flb"
    ORA-27037: unable to obtain file status
    Linux Error: 2: No such file or directory
    Additional information: 3
    


  4. Investigate the alert log on collabn1 – do any error messages appear here? Do any other problems occur?

  5. Disable flashback database. You do not need to shutdown for the disable operation.

    SQL> alter database flashback off;
    Database altered.