Scheduling Database Log Backups Using Disk Caching

Applies to: Microsoft SQL Server on Windows, Oracle (but not Oracle RAC), and SAP HANA

Create a schedule to automatically back up the database logs to a MediaAgent cache. You can also define the frequency when you want the CommServe computer to commit the cached database log backups on the media.

For SAP HANA agents, when you create a schedule to automatically back up the database logs to the MediaAgent, the logs are moved to the cache when the log segments become full or when the log backup intervals are met. Also, you can specify the schedule frequency when the CommServe computer will commit the logs on the media.

Take the following into consideration when planning the schedule:

• The number of transactions that the database generates

• The log file size

The Detect file or log activity every setting defines how often the software checks whether the log files need to be backed up to the MediaAgent. The software does not check the database threshold settings during this interval. When this interval expires, the software checks whether the log files need to be backed up.

The Force a backup every setting ensures that the software backs up the logs even when the threshold settings are not met. For example, if the parameter is set to 24 hours and the software has not run a log backup in that time, the software starts a log backup without checking the log backup settings. When the interval expires, the software checks whether the log files were backed up. The software looks at the backup finish time and whether the backup occurred during the Detect file or log activity every interval.

If you assign this schedule type to a subclient that has no backups before the assignment, the first backup runs irrespective of the database threshold settings.

The following best practices apply to all the agents:

• Set a low Detect file or log activity every interval. For example, set a minimum interval of 15 minutes.

• Set a Force a backup every interval that is less than the time interval between running two backups.

• Set the option to perform a log backup when the log utilization approaches 50%-80%. The actual value depends on the storage size.

You can also configure a schedule policy for automatic database log backups using the disk caching of logs feature. For information about how to configure a schedule policy, see Adding an Automatic Database Log Backup Schedule to a Schedule Policy.

Best practice: For some agents, such as the Oracle agent, the Commvault software creates a default archive log subclient. Do not modify the properties of the default archive log subclient.

Procedure

1. From the CommCell Browser, go to Client Computers > client > agent > instance.

2. Right-click the subclient, and then click Backup.

   The Backup Options for Subclient dialog box appears.

3. On the Backup Options tab, select a backup type depending on the type of database.

   For example, for Oracle, select a backup type of Full. For SQL Server, select a backup type of Transaction Log.

4. On the Backup Options tab, select Schedule, and then click Configure.

   The Schedule Details dialog box appears.

5. In the Schedule Name box, enter a unique name for the schedule.

6. Select Automatic.

7. In the Detect file or log activity every box, enter the interval after which the software checks whether the log files qualify for a backup.

   When this time expires, the Commvault software checks the criteria and automatically starts a backup if any of the criteria are met.

8. In the Force a backup every box, enter the interval when the software checks whether the log files were backed up.

   If this value is met, the log backup starts, regardless of whether the database criteria are met.

9. Select the criteria to use to run backup jobs:

10. Database	Option
    Oracle	Note Don't enable disk caching of archive log backups for Oracle source instances that have Live Sync configured, because Live Sync will be disabled as a result. If disk caching is enabled at the plan level or in a schedule policy, you must use a different plan, one that doesn’t have disk caching enabled, for the source Oracle instance. Support for Oracle Live Sync with instances that have disk caching of log backups enabled will be added in a later release. Disk caching of archive log backups is not supported with Unified Data Guard configurations. To run a log backup when the number of log files on the disk use a specified amount of the storage space, select the Start backup when disk at log destination is option. To run a log backup when the number of log files on the disk reach a specified number, select the Number of Archived Logs in Log destination option. Select the Use disk cache for log backups and commit every check box and enter the interval of time between each log commit operation to the CommServe server. For more information about the feature, see Disk Caching for Frequent Log Backups. Best practice: If the Disk Caching for Frequent Log Backups feature is enabled for Oracle and you have configured selective online full backups for the instance, use the same storage policy for the log backups defined at the instance level and for the selective online full backups defined at the subclient level. If you configure different storage policies for log backups and data backups and the Disk Caching for Frequent Log Backups feature is turned on, the log backup uses the storage policy configured for the instance and the data backup uses the storage policy configured for the subclient. For information about selective online full backups for Oracle, see Configuring Oracle Selective Online Full Backups.
    SAP HANA	Select the Use disk cache for log backups and commit every check box and enter the interval of time between each log commit operation to the CommServe server. For more information about the feature, see Disk Caching for Frequent Log Backups.
    SQL	To run a log backup when the used space of the log file reaches a specified percentage, select the Start the backup when the log file is option. Select the Use disk cache for log backups and commit every check box and enter the interval of time between each log commit operation to the CommServe server. For more information about the feature, see Disk Caching for Frequent Log Backups. Note Only databases that use the full recovery model are eligible for automatic log backups.

11. Click OK to close the Schedule Details dialog box.

12. Click OK to close the Backup Options for Subclient dialog box.