Wednesday, January 27, 2010

Redo Log File Status

To see the status of the redo log file there are two dynamic views are there.
A)V$LOG
B)V$LOGFILE

A)V$LOG:
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V$LOG displays redo log file information from the control file.

Status:
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1)UNUSED - Online redo log has never been written to. This is the state of a redo log that was just added, or just after a RESETLOGS, when it is not the current redo log.

2)CURRENT - Current redo log. This implies that the redo log is active. The redo log could be open or closed.

3)ACTIVE - Log is active but is not the current log. It is needed for crash recovery. It may be in use for block recovery. It may or may not be archived.

4)CLEARING - Log is being re-created as an empty log after an ALTER DATABASE CLEAR LOGFILE statement. After the log is cleared, the status changes to UNUSED.

5)CLEARING_CURRENT - Current log is being cleared of a closed thread. The log can stay in this status if there is some failure in the switch such as an I/O error writing the new log header.

6)INACTIVE - Log is no longer needed for instance recovery. It may be in use for media recovery. It might or might not be archived.

B)V$LOGFILE:
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V$LOGFILE view contains information about redo log files.
1)INVALID - The file is corrupted or missing.
2)STALE -This redo log file member is new and has never been used.
3)DELETED -The file is no longer being used.
4) -The redo log file is in use and is not corrupted.

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