Database Reference
In-Depth Information
Here is some sample output:
GROUP# THREAD# GRP_STATUS MEMBER MEM_STA MBYTES
------ -------- ---------- ------------------------------ ------- --------
1 1 INACTIVE /u01/oraredo/O12C/redo01a.rdo 50
1 1 INACTIVE /u02/oraredo/O12C/redo01b.rdo 50
2 1 CURRENT /u01/oraredo/O12C/redo02a.rdo 50
2 1 CURRENT /u02/oraredo/O12C/redo02b.rdo 50
3 1 INACTIVE /u01/oraredo/O12C/redo03a.rdo 50
3 1 INACTIVE /u02/oraredo/O12C/redo03b.rdo 50
If only one member of a multiplexed group has experienced a failure, then proceed to the section on “Restoring
After Losing One Member of Multiplexed Group”. If all members of a redo log group have experienced a failure and
your database is open, it will hang (cease to allow transactions to process) as soon as the archiver background process
cannot successfully copy the failed online redo log file members. If your database is closed, Oracle will not allow you
to open it if all members of one online redo log group are experiencing a media failure. When you attempt to open
your database, you'll see a message similar to this:
ORA-00313: open failed for members of log group...
Depending on the status reported in V$LOG for the failed group, use Table 7-1 to determine what action to take.
Your target database's alert.log file contains the best information for determining what type of failure has
occurred. If only one member of a multiplexed group fails, then you will be able to detect this only by inspecting
the alert.log file. You can also try to stop and start your database. If all members of a group have experienced media
failure, then Oracle will not let you open the database and will display an ORA-00313 error message.
The alert.log file will also tell you where additional error messages have been written to trace files:
Additional information: 3
Checker run found 1 new persistent data failures
Errors in file /u01/app/oracle/diag/rdbms/o12C/O12C/trace/O12C_lgwr_10531.trc:
When diagnosing online redo log issues, the V$LOG , V$LOGFILE , and V$LOG_HISTORY views are particularly helpful.
You can query these views while the database is mounted or open. Table 7-2 briefly describes each view.
Table 7-2. Useful Views Related to Online Redo Logs
View
Description
V$LOG
Displays the online redo log group information stored in the control file.
V$LOGFILE
Displays online redo log file member information.
V$LOG_HISTORY
History of online redo log information in control file.
The STATUS column of the V$LOG view is particularly useful when working with online redo logs groups. Table 7-3
describes each status and meaning for the V$LOG view.
 
 
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