Database Reference
In-Depth Information
Table 7-3. Status for Online Redo Log Groups in the V$LOG View
Status
Meaning
CURRENT
The log group that is currently being written to by the log writer.
ACTIVE
The log group is required for crash recovery and may or may not have been archived.
CLEARING
The log group is being cleared out by an alter database clear logfile command.
CLEARING_CURRENT
The current log group is being cleared of a closed thread.
INACTIVE
The log group isn't needed for crash recovery and may or may not have been archived.
UNUSED
The log group has never been written to; it was recently created.
The STATUS column of the V$LOGFILE view also contains useful information. This view contains information
about each physical online redo log file member of a log group. Table 7-4 provides descriptions of the status of each
log file member.
Table 7-4. Status for Online Redo Log File Members in the V$LOGFILE View
Status
Meaning
INVALID
The log file member is inaccessible, or it has been recently created.
DELETED
The log file member is no longer in use.
STALE
The log file member's contents are not complete.
NULL
The log file member is being used by the database.
It's important to differentiate between the STATUS column in V$LOG and the STATUS column in V$LOGFILE . The
STATUS column in V$LOG reflects the status of the log group. The STATUS column in V$LOGFILE reports the status of the
physical online redo log file member.
Restoring After Losing One Member of Multiplexed Group
Suppose you notice this message in your alert.log file:
ORA-00312: online log 2 thread 1: '/u02/oraredo/O12C/redo02b.rdo'
You know that this group is multiplexed but only see an error with one of the members of the group. If your online
redo log file members are multiplexed, the log writer will continue to function as long as it can successfully write to
one member of the current log group. If the problem is temporary, then as soon as the online redo log file becomes
available, the log writer will start to write to the online redo log file as if there were never an issue.
If the media failure is permanent (such as a bad disk), then you'll need to replace the disk and drop and re-create
the bad member to its original location. If you don't have the option of replacing the bad disk, then you'll need to drop
the bad member and re-create it in an alternate location.
 
 
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