Loss Of Redo Logs

The following sections describe the appropriate recovery strategies for these situations:

	Recovering After Losing a Member of a Multiplexed Online Redo Log Group
	Recovering After the Loss of All Members of an Online Redo Log Group

If you have lost multiple groups of the online redo log, then use the recovery method for the most difficult log to recover. The order of difficulty, from most difficult to least, follows:

The current online redo log
An active online redo log
An unarchived redo log
An inactive online redo log

Recovering After Losing a Member of a Multiplexed Online Redo Log Group

If the online redo log of a database is multiplexed, and at least one member of each online redo log group is not affected by the media failure, Oracle allows the database to continue functioning as normal. Oracle writes error messages to the LGWR trace file and the alert.log of the database.

Solve the problem by taking one of the following actions:

	If the hardware problem is temporary, then correct it. LGWR accesses the previously unavailable online redo log files as if the problem never existed.
	If the hardware problem is permanent, then drop the damaged member and add a new member using the procedure below.

Locate the filename of the damaged member in V$LOGFILE. The status is INVALID if the file is inaccessible:

SELECT group#, status, member FROM v$logfile;

GROUP#    STATUS       MEMBER
-------   -----------  ---------------------
0001                    /oracle/dbs/log1a.f
0001                    /oracle/dbs/log1b.f
0002                    /oracle/dbs/log2a.f
0002      INVALID       /oracle/dbs/log2b.f
0003                    /oracle/dbs/log3a.f
0003                    /oracle/dbs/log3b.f

Drop the damaged member. For example, to drop member log2b.f from group 2, issue:

svrmgr> Alter database drop logfile member '/oracle/dbs/log2b.dbf';

Add a new member to the group. For example, to add log2c.f to group 2, issue:
svrmgr> Alter database add logfile member '/oracle/dbs/log2c.dbf' to group 2;

NOTES: If the file you want to add already exists, then it must be the same size as the other group members, and you must specify REUSE:
```
ALTER DATABASE ADD LOGFILE MEMBER '/oracle/dbs/log2b.f' REUSE TO GROUP 2;
```

Send mail to mike@infomaxweb.com with questions or comments about this web site. Copyright © 2003 Infomax Last modified: 10/27/06

Send mail to mike@infomaxweb.com with questions or comments about this web site.
Copyright © 2003 Infomax
Last modified: 10/27/06