BRTOOLS-Backup issues

Ending a Backup After an Instance Failure or SHUTDOWN ABORT:

The following situations can cause a tablespace backup to fail and be incomplete:

The backup completed, but you did not run the ALTER TABLESPACE ... END BACKUP statement.
An instance failure or SHUTDOWN ABORT interrupted the backup.

Whenever crash recovery is required, if a datafile is in backup mode when an attempt is made to open it, then the database will not open the database until either a recovery command is issued, or the datafile is taken out of backup mode.

For example, the database may display a message such as the following at startup:

ORA-01113: file 12 needs media recovery
ORA-01110: data file 12: '/oracle/dbs/tbs_41.f'

If the database indicates that the datafiles for multiple tablespaces require media recovery because you forgot to end the online backups for these tablespaces, then so long as the database is mounted, running the ALTER DATABASE END BACKUP statement takes all the datafiles out of backup mode simultaneously.

In high availability situations, and in situations when no DBA is monitoring the database, the requirement for user intervention is intolerable. Hence, you can write a crash recovery script that does the following:

1. Mounts the database
2. Runs the ALTER DATABASE END BACKUP statement
3. Runs ALTER DATABASE OPEN, allowing the system to come up automatically

An automated crash recovery script containing ALTER DATABASE END BACKUP is especially useful in the following situations:

All nodes in an Oracle Real Application Clusters (RAC) configuration fail.
One node fails in a cold fail over cluster (that is, a cluster that is not a RAC configuration in which the secondary node must mount and recover the database when the first node fails).

Alternatively, you can take the following manual measures after the system fails with tablespaces in backup mode:

Recover the database and avoid issuing END BACKUP statements altogether.
Mount the database, then run ALTER TABLESPACE ... END BACKUP for each tablespace still in backup mode.

Ending Backup Mode with the ALTER DATABASE END BACKUP Statement

You can run the ALTER DATABASE END BACKUP statement when you have multiple tablespaces still in backup mode. The primary purpose of this command is to allow a crash recovery script to restart a failed system without DBA intervention. You can also perform the following procedure manually.

To take tablespaces out of backup mode simultaneously:

1. Mount but do not open the database. For example, enter:

SQL> STARTUP MOUNT

2. If performing this procedure manually (that is, not as part of a crash recovery script), query the V$BACKUP view to list the datafiles of the tablespaces that were being backed up before the database was restarted:

SQL>  SELECT * FROM V$BACKUP WHERE STATUS = 'ACTIVE';
FILE#      STATUS             CHANGE#    TIME   
---------- ------------------ ---------- ---------
        12 ACTIVE                  20863 25-NOV-02
        13 ACTIVE                  20863 25-NOV-02
        20 ACTIVE                  20863 25-NOV-02
3 rows selected.

3. Issue the ALTER DATABASE END BACKUP statement to take all datafiles currently in backup mode out of backup mode. For example, enter:

SQL> ALTER DATABASE END BACKUP;

You can use this statement only when the database is mounted but not open. If the database is open, use ALTER TABLESPACE ... END BACKUP or ALTER DATABASE DATAFILE ... END BACKUP for each affected tablespace or datafile.



Caution:

Do not use ALTER DATABASE END BACKUP if you have restored any of the affected files from a backup.




Ending Backup Mode with the SQL*Plus RECOVER Command

The ALTER DATABASE END BACKUP statement is not the only way to respond to a failed online backup: you can also run the SQL*Plus RECOVER command. This method is useful when you are not sure whether someone has restored a backup, because if someone has indeed restored a backup, then the RECOVER command brings the backup up to date. Only run the ALTER DATABASE END BACKUP or ALTERTABLESPACE ... END BACKUP statement if you are sure that the files are current.



Note:

The RECOVER command method is slow because the database must scan redo generated from the beginning of the online backup.




To take tablespaces out of backup mode with the RECOVER command:

1. Mount the database. For example, enter:

SQL> STARTUP MOUNT

2. Recover the database as normal. For example, enter:

SQL> RECOVER DATABASE

3. Use the V$BACKUP view to confirm that there are no active datafiles:

SQL>  SELECT * FROM V$BACKUP WHERE STATUS = 'ACTIVE';
FILE#      STATUS             CHANGE#    TIME   
---------- ------------------ ---------- ---------
0 rows selected.