About retention control

A data retention policy is determined by an organization's legal and business data retention requirements. You may need to keep data available for months or even years. How you achieve this may be a combination of on-system retention and archiving to removable media for longer term storage.

Space on the system is self-managed based on the user settings for balancing ingest rate and retention (see Balancing backup performance and retention). When your system capacity is full, the oldest backups are purged to make room for newer ones. However, the Unitrends system will not purge the latest backups of any type for a given client, or any backups for a client that are put on legal hold. The greater the difference in the amount of total data protected and the system size, the greater the on-system retention. If the difference is small you will see less retention on the system. If you require many weeks of on-system retention, you must deploy a system of sufficient size.

The retention control feature allows you to decide how long backups are retained on the system before being purged. Controlling the order in which backups are removed allows for more effective management of available space, without affecting the manner in which general performance is balanced with retention.

The Retention tool tracks backups as groups containing a master or full backup, along with any incrementals or differentials that followed. A master in a file-based backup group may be generated on-demand, by a scheduled backup, or synthesized by the system during an incremental forever process.

No retention policy is set for newly added clients. With no retention policy set, backups for a client are kept as long as possible by a system until the system runs out of backup space, at which point the oldest backups are purged. Retention policies are set using the following controls. You must have Manage privileges or higher to change retention settings.

Retention control

Description

Min retention goal

A notification mechanism to inform when the desired retention goals are not being met. Setting the minimum retention goal does not guarantee the retention of protected data for the defined period. As newer backups are performed (scheduled or immediate), older backups are purged to reclaim space on the system if necessary. If guaranteed minimum retention is needed, use legal hold. If the minimum retention goal is not met, a message displays on the Alerts Last 7 Days tab of the Status screen.

Max retention limit

Number of days backups are retained if space allows. Backups are deleted once the full has exceeded this limit. When a full backup exceeds its retention, the full and all associated incrementals and differentials are purged as well. If you set the maximum retention limit below the minimum limit, backups are deleted and the process cannot be stopped.

Note: The most current backup group for a client is never purged from the system regardless of the need for space.

Legal hold

Unlike Min retention goal, Legal hold allows you to set a hard minimum limit on the number of days a backup will be held. The legal hold setting takes precedence over the Min and Max retention settings. Backups that are younger than the legal hold limit are not purged for any reason, including at the expense of new, incoming backups. For legal hold purposes, the age of a backup is only considered to be as old as the latest backup in a set, e.g., the last incremental before a new full. After passing the legal hold limit, the min retention goal and max retention limit settings take over for the purposes of retention. If legal hold is preventing new backups from occurring, a message displays on the Alerts Last 7 Days tab of the Status screen. Information about backups that have been placed on legal hold can be found in the Legal Hold report. See Legal Hold Backups Report for details.

Legal hold example

In the following diagram, a backup (B1) generated on March 21st, 2013, is set to Legal Hold for four days. There are subsequent differentials on the 22nd, 23rd, and 24th of March 2013. B1 is four days old on March 25th, 2013, and there is a new master, B5. However, B1 cannot yet be purged because its purging would result in the purging of the entire G1 group, including differentials B2, B3, and B4, which are less than four days old. When the most recent backup in the group (B4) is four days old on March 28th, the entire G1 group reverts to using minimum and maximum retention settings and is eligible for purging. A new backup is added to a group as soon as it is queued, so a group is only as old as its most recent backup.

Legal_hold2.png

 

For more information on retention settings, see To set or view retention goals and limits.