How data lifecycle management in Backup Exec 2012 manages backup set retention on disk storage
| Article:TECH201826 | | | Created: 2013-01-18 | | | Updated: 2013-04-17 | | | Article URL http://www.symantec.com/docs/TECH201826 |
Problem
Prior to Backup Exec 2012, Backup Exec used media sets to manage the lifecycle of backup data. The tape-centric method managed removable media like tape, and also managed data that is backed up to .BKF container files (an emulated-tape disk container file) on disk-based storage.
Two issues that result from using media sets to manage backup data for disk-based storage are:
· No guarantee of backup data integrity for recovery
Media sets cannot ascertain the data dependency between full and incremental backups. Instead, you must know how to configure two media sets that have the correct overwrite and append periods for the full backup and the incremental backup to avoid prematurely overwriting any media that is required for recovery. Incremental backup data is not useful if the previous incremental or full backup data is not available.
· Inefficient reclamation of disk storage
The disk storage that is used by expired backup data is not reclaimed in a timely manner because the lifecycle of backup data is managed by media, not by the backup data itself. The media is not overwritten until all of the backup sets on the media have expired. Ideally, the expired backup data should be deleted immediately to free disk space for new backup jobs.
Solution
The Backup Exec 2012 data lifecycle management (DLM) feature manages the expiration of backup data that is stored on disk-based storage.
Note: You must continue to use media sets to manage data retention on removable disk cartridge storage and on tape storage.
Following are some important points about data lifecycle management.
About data retention
· The retention of backup data is associated with a backup set instead of with the media.
· The retention of backup data is a property of the job definition and uses a single retention value, such as 4 weeks. It is not a property of a media set with both an overwrite period and an append period. When you create a backup job that is sent to a disk-based storage device, you specify how long to keep backup data. When the amount of time to keep the backup data expires, data lifecycle management deletes the backup sets and frees the disk space.
About the single backup set .bkf file
· A .bkf file can contain only one backup set or a partial backup set. Backup sets are no longer appended to or overwritten on a .bkf file. Data lifecycle management deletes any expired backup sets, including those on .bkf files, to free disk space.
· A backup set can span over more than one .bkf file.
About the data lifecycle management grooming process
· Data lifecycle management checks for expired backup sets and then grooms those backup sets and the associated backup data to free disk space.
· Data lifecycle management runs every 4 hours and whenever a low disk storage alert is received.
· Data lifecycle management checks the dependency between the full and the associated incremental or differential backup sets to prevent breaking a chain of full/incremental or full/differential backup sets. Data lifecycle management does not groom expired full and incremental backup sets if there is a dependent incremental backup set that has not expired.
· Data lifecycle management does not delete the last copy of the latest recovery point chain. A recovery point chain is the associated full and incremental backup sets that are generated from the same job for the same resource using the same selection list, for example, \\Server\C:, \\Server\MSSQL\BEDB). These are the backup sets that are required to successfully recover a resource to the latest point-in-time.
About deleting backup sets
· When you attempt to delete a backup set, Backup Exec checks the backup set to ensure that there are no dependent backup sets. Backup sets from incremental and differential jobs are dependent on the backup sets that come from the full backup job in the same backup definition. When Backup Exec detects dependent backup sets, it gives you an option to either cancel the delete operation, or to delete the backup set and any dependent backup sets.
· When Backup Exec deletes a backup set, it also deletes all of the backup set’s associated backup data from disk storage.
About retaining backup sets
· To prevent backup sets from automatically expiring, you can manually retain the backup set. When you retain a backup set, you can specify a reason and add a description. Data lifecycle management does not groom retained backup sets or any backup sets on which the retained backup set is dependent.
· To let retained backup sets expire, you must remove the backup sets’ retained status. After you release retained backup sets, data lifecycle management expires the backup sets automatically when it runs. The delete operation is disabled for retained backup sets.
Storage options in Backup Exec that affect data lifecycle management
· Limit Backup Exec to read-only operations
This option on the device property page prevents data lifecycle management from running on a specific disk-based storage device that you reattach. This option applies only when the storage device has been absent from the Backup Exec server for the number of days that you specify in the global setting.
To see this option, on the Storage tab, double-click the storage device. Then, in the left pane, click Properties.
· Limit Backup Exec to read-only operations on a storage device if it has been detached for at least x days
This global setting prevents Backup Exec from deleting expired backup sets on any disk-based storage device as soon as you reattach it. When you limit Backup Exec to read-only operations, you have time to review any expired backup sets and determine if you want to keep them before data lifecycle management deletes them. Backup Exec is limited to read-only operations only on the disk-based storage devices that are detached from the Backup Exec server for the specified number of days.
To see this option, click the Backup Exec button, click Configuration and Settings, and then click Backup Exec Settings. In the left pane, click Storage.
Note: The job run to such disk storage with this option Limit Backup Exec to read-only operations enabled, might stay in queued state and disabling this option may be required.
· Low disk space
This device property is the first of three low disk space conditions. When the storage device’s used capacity reaches this threshold, the data lifecycle management feature immediately searches the device for expired backup sets that it can delete.
To see this option, on the Storage tab, double-click the storage device. Then, in the left pane, click Properties.
You can review the best practices for data lifecycle management at the following URL: http://entsupport.symantec.com/umi/V-269-43
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Article URL http://www.symantec.com/docs/TECH201826
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