About retention rules

Retention rules allow you to implement granularity for backed up generations. For example, you might want to retain all generations from the previous day, then 1 generation each day for a week, 1 generation each week for a month, 1 generation each month for a year, and 1 generation each year for the next 10 years. When using retention, you must know the nature of the backup set data such as number of generations and frequency of changes.

Retention rules are optional. If you do not use the retention feature, your backup data remains online based on the backup set item maximum generation settings. The oldest generation of a file will be overwritten if the maximum number of generations is reached. Generations are created on the online storage when the backup detects that a file has changed. Files that never change have only one generation on the DS-System online storage.

As a best practice, you should create specific retention rules, and avoid combining the different types. For example, if you have a backup set that uses local storage, create a specific local storage retention rule. If you combine two or more of the above types, then some overlapping of the rules can occur which will affect the behavior of the retention.

NOTE: Obsolete data is what the retention rule determines should be deleted. For safety, especially when testing new retention rules, you can configure retention to send all the obsolete data to BLM Archiver, while deleting from DS-System online storage.

After assigning a retention rule to a backup set, you can enforce the rule either on demand or on a schedule. When a retention rule is enforced, any data that does not qualify for retention is deleted.

This type of retention uses time-based rules to determine what data to keep online. All other data is considered obsolete. If the Move obsolete data to BLM option is not selected, obsolete data is permanently deleted.

• Keep most recent generations — Removes all generations of a file from the DS-System online storage with the exception of the latest (most recent) generation. If this number is very high (e.g. 9999), all the other time-based rules specified in this retention rule will not have any effect because they will be over-ruled by this particular rule. This option has a default value of 1

• Keep all generations for [x] interval of time for [y] interval of time — Allows you to define a very precise time-based online retention rule.

The Delete Options for files that have been removed from the backup source will always apply. They are the first rules that apply when a retention rule is enforced on a backup set.

If the Move obsolete data to BLM option is not selected, data that is not retained online is permanently deleted.

• Once you enforce this retention rule on a backup set, it applies the options configured for the files that are removed from source, and for data that has been moved by a third-party HSM/ILM solution to a remote location.

• Once the file has been removed from the source machine, you can configure this retention rule to keep [x] number of generations for each file in the backup set for a specific period. DS-Client detects if files have been removed from source during the backup process.

• If Windows DS-Client detects a placeholder / stub is on the source machine, retention can delete all file generations backed up before the placeholder / stub, or it can delete all generations that are not a placeholder / stub and were backed up in an earlier session.

• By default, enforcing any retention rule deletes all obsolete data from the DS-System online storage. However, a copy of this data can be sent to BLM Archiver before it is removed completely from the DS-System online storage.

Every time you delete dats, you have the option to send a copy of the generations that are about to be deleted to the BLM Archiver. If Archive old data to BLM is used with other retention rule types, it is applied last, and only to the files that remain online after the Delete Options and Time Retention Options have run.

You specify the age of the files to move to BLM Archiver. Retention compares the last modification date with the backup session date and applies the older of the two for the archiving rules. For example, if all files older than one month should be sent to the BLM Archiver, DS-Client will compare the last modification time and backup time of a file. It takes the oldest value to calculate the age of the file.

This type of retention is used with the Local Storage feature. This only applies to the files saved in the DS-Client Local Storage.

To have the DS-Client save multiple generations on the local storage, the backup set must be assigned to a retention rule that has the Local Storage Retention options enabled. Data is kept on the Local Storage only if the same generation also exists on the DS-System online storage.