As we know that SYSTEM – stores the data dictionary.  Being an Oracle DBA we all know the importance of SYSTEM tablespace.  In these below lines, we can have actual technical knowledge about system’s information.

SYSTEM – a tablespace that is always used to store SYSTEM data that includes data about tables, indexes, sequences, and other objects – this metadata comprises the data dictionary.

  • Every Oracle database has to have a SYSTEM tablespace—it is the first tablespace created when a database is created.
  • Accessing it requires a higher level of privilege.
  • You cannot rename or drop a SYSTEM tablespace.
  • You cannot take a SYSTEM tablespace offline.
  • The SYSTEM tablespace could store user data, but this is not normally done—a good rule to follow is to never allow the storage of user segments in the SYSTEM tablespace.
  • This tablespace always has a SYSTEM Undo segment.

From the above information, i hope you get the hint that why do we need a backup of system tablespace and why do we need to recover.

 

What does it happen when a corrupt block is related to SYSTEM datafile?
Let’s simulate this scenario:

DBVERIFY detects your SYSTEM datafile is corrupt. Five data blocks are no more available.

Let’s update the V$DATABASE_BLOCK_CORRUPTION view issuing a backup validate command.

The V$DATABASE_BLOCK_CORRUPTION view contains the list of corrupt blocks, all related to datafile number 1.

Let’s try to recover those blocks.

It worked. And the view doesn’t contain any data.

So the recovery process of a corrupt block of the SYSTEM tablespace is the same and there is no need to bounce the instance.

Thank you for giving your valuable time to read the above information.

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Comments

  1. Naresh

    Nice Explanation … Still having few doubts !!

    1) Is “BLOCKRECOVER CORRUPTION LIST” and “recover corruption list” both command are different ?
    2) How to recover block corruption when we don’t have backup ?

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