Performing an Oracle Log Backup
Use log backups in the following scenarios.
- To restore the database to the most recent state after a database failure.
- To restore specific logs, which are identified using a serial number or identification tag that are missing in the database.
- To restore logs from a specific time range that were lost due to a hard disk corruption. Use a point-in-time archive log restore.
The current redo log file is closed (even if it is not filled up completely) and the next redo log file is used for writing using a log switch during an archive log backup. The closed redo log file is then archived during the log phase.
Best Practice: Configure a schedule to back up the logs before the archive log destination fills up to 80% of the space (Backup Task Options dialog box, Schedule Pattern tab, Start backup when disk at log destination is box). For information on how to configure an automatic schedule, see Creating an Automatic Schedule for Database Log Backups.
Note: When you choose any advanced backup option on the Advanced Backup Options dialog box, Delete Archive Logs tab, the software will only delete logs that have been backed up at least 1 time. To ensure this, the software automatically adds the following line to the RMAN script.
delete noprompt archivelog all backed up 1 times to sbt ;
Before You Begin
- Configure a subclient for Oracle Archive Log Backups.
- From the CommCell Browser, expand Client Computers > client > Oracle > instance.
- Right-click the subclient configured for the archive log backup and then click Backup.
- On the Backup Options for Subclient dialog box, select the backup type and initiation:
- In the Backup Type section, choose the backup type.
- If you selected the Cumulative check box, specify the backup incremental level in the Oracle Incremental Level box.
- In the Job Initiation section, specify whether to run the backup now or if it will be scheduled.
Note: If you selected Schedule, set up the schedule.
For information on configuring a backup schedule, see Schedule Backups.
- Click Advanced.
The Advanced Backup Options dialog box appears.
- Select the option to determine the logs to back up and delete.
On the Backup Archive Logs tab, and Delete Archive Logs tab:
Select the Delete Archive Logs check box and Backup Archive Logs check box.
Choice Description All Backs up or deletes all logs Older than n Days Backs up or deletes logs older than the specified number of days Not Older than n Days Backs up or deletes logs not older than the specified number of days By Log Time Backs up or deletes logs in the specified time range.
Select the Start Time and End Time check boxes and enter the start and end times of the logs.
If you only specify the start log time, all logs are backed up from the start time to the current time.
By Log Seq Num Backs up or deletes logs in a specified sequence range.
The Log Sequence Number uniquely identifies an archive log. For example, if you create a database with two online log files, then the first file is assigned log sequence number1. When the first file fills, Oracle switches to the second file and assigns a log sequence number of 2.
Select the Start Sequence Number and End Sequence Number check boxes and enter the beginning and ending sequence numbers
By Sys change Num Backs up or deletes logs in the specified System Change Number range.
The SCN is a stamp that defines a committed version of a database at a point in time. Oracle assigns every committed transaction a unique SCN. For example, SCNs of two successive committed transactions could be 576601 and 576799.
Select the Start Sys chg Num and End Sys chg Num check boxes and enter the beginning and ending SCNs:
The end serial number must be greater than or equal to the start serial number. •
The start and the end SCN cannot be 0.
If you provide only the start SCN, is the only one provided, only the logs starting that start from that sequence number are backed up.
Like Backs up or deletes logs with a file name that starts with a specified string.
Enter the string to match.
Not Backed up Backs up or deletes logs that have not been backed up a specified number of times.
Enter the number of times a log must be backed up.
- On the Backup Archive Logs tab, specify the location where the backed up logs are stored:
- Select the Archive Log Destinations for Backup check box.
- Click Add.
- On the Select an Archive Log Destination dialog box enter the full path to the directory where backed up archive logs will be stored.
- Click OK to close the Select an Archive Log Destination dialog box.
- Optional: Uniquely identify a backup. On the Oracle Options tab, enter a unique tag.
You can include variables in the tag. For supported tag variables, see Oracle Tag Variables.
The Oracle tag you that you specify for the backup overrides the tag defined for the subclient.
- Optional: Set the backup load distribution across disks to improve performance. For more information, see Configuring the Disk Ratio for Oracle RMAN.
- Click OK to close the Advanced Backup Options dialog box.
- Click OK to close the Backup Options dialog box.