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      Most common Oracle 
    database failures are: 
       
    - backup files not recognizable by RDBMS 
    - database locked as 'suspect' preventing access 
    - deleted,dropped or 
    truncated tables  
    - accidentally deleted records  
    - corrupted database files and devices 
    - damaged individual data blocks  
    - accidentally overwritten database files and devices, etc. 
      
    Software failure includes problems 
    such as missing db-files, blocks, or rows in the database. Oracle Server has 
    the highest chance in this kind of failure.  
    At startup, if a database is found to have 
    corrupted blocks, an out-of-bounds row identifier (RID), or corrupt indexes, 
    it will be marked suspect and no other transactions will be allowed in the 
    database. If these types of errors occur during normal database operation, 
    they almost always indicate a serious problem, and the problem should be 
    corrected immediately.  
    and then 
    - after a security update of oracle server 
    the database did not start again 
      - getting several errors when starting the database like ORA-01251, 
      ORA-00600, 
      - there seems to be something wrong
      with the header of your datafiles, 
      - you tried to recreate the control files, but oracle is not accepting the
      datafiles 
      - there is no backup from the db
      available, 
      - Oracle DBA Senior says : FORGET !! 
      - media recovery cannot recover the datafile, 
      - Oracle Data Unloader Utility DUL may be your only 
    solution but it is very
      expensive !!! 
      - you have any datafile from your DB (*.ORA, *.DBF). 
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