How do I configure my backup retention policy in PHDVB 6.5?


Setting up and understanding backup retention policy. Detailed examples.


The retention policy (how long to keep backups for each virtual machine) is configured using the PHD Virtual Backup Console, Configuration page.

Backup Retention tab

Use the Retention tab to define your backup retention policy. Backup retention differs based on the backup mode you're using. The Virtual Full Retention Policy options are used to set the retention for any Virtual Full backups taken by the PHD VBA. The Incremental Retention Policy applies to the Full/Incremental backups taken by the PHD VBA.

Note:When Backup Archive - Backup Data Store Sync mode is enabled, Retention is set to Keep All and cannot be changed.

Virtual Full Retention Policy

By default, PHD Virtual Backup will keep the 5 most recent virtual full backups for each VM as well as a backup from the last 7 days, one backup from each of the last 4 weeks, 12 months, and 5 years. Using the Retention options, you can select how many backups you want to keep for each virtual machine to meet your individual compliance and storage requirements. When a retention policy is set, a system job runs (Delete trim) and performs the retention processing at the top of each hour.

You can select to use pre-defined settings, or you can set specific values for each setting. The available settings are:

  • Keep All- Retain all backups for all VMs. This is the default setting.
  • Typical- Retain the 5 most recent backups as well as the most recent backup from each of the last 7 days, 4 weeks, 12 months, and 5 years.
  • Custom- You define the values for each retention setting.

Incremental Retention Policy

To recover Full/Incremental backups, a full backup and all related incremental backups must exist (a full backup with all required incremental backups is known as a backup 'chain'). To avoid breaking a full/incremental backup chain, which would result in backups that cannot be restored, for full/incremental backups, retention is defined per-chain. The default setting will keep the last two chains for each VM. If you take weekly full backups, your backup chains for each VM will consist of a single full and then six incremental backups. The default retention settings of 2 will then result in 2 weeks of backup data for each VM. If you schedule monthly fulls, you will end up with 2 months of backup data per VM (2 fulls and up to 60 incremental backups depending on the current month).

Retention Notes

  • Full/Incremental backup retention policy is based on backup chains - the value set within the Incremental Retention Policy area of the dialog. The values within the Virtual Full Retention Policy area (Days, Weeks, etc) apply only to virtual full backup types - not full or incremental backups.
  • Days start at 00:00:00 and include the current day.
  • Weeks start on Monday and include the current week.
  • Months are based on the calendar month and include the current month.
  • Years are based on the calendar year and include the current year.
  • Retention adjusts for Daylight Savings Time.
  • Backup files marked as Archive will never be deleted.

To define backup retention settings

  1. Open the PHD Virtual Backup Console and click Configuration.
  2. Select the appliance you want to configure from the Select the appliance to configure menu.
  3. Click the Retention tab then use the options available to set your retention policy.
  4. When finished, click Save.

To keep only a certain number of Virtual Full backups per VM

  1. Open the PHD Virtual Backup Console and click Configuration.
  2. Select the appliance you want to configure from the Select the appliance to configure menu.
  3. Click the Retention tab then, in the Virtual Full Retention Policy options, select Custom.
  4. Set the Recent backups to keep to the number of backups you would like to keep for each VM. For example, to keep only 5 backups for each VM, set this value to 5.
  5. Set the Days, Weeks, Months, and Yearsvalues to 0.
  6. When finished, click Save.

    In this example, only the last five backups will be kept for each VM.

Advanced Retention Scenario (Virtual Full backups)

The following example scenario describes how virtual full backups are retained when using advanced retention settings. We will assume the following:

  • Today is 10/29/2012
  • Backup Frequency is set to Daily (and the daily backup has run today)
  • Backups have been collected for the last 5 years
  • Virtual Full Retention Settings set to Custom with Recent backups set to 3, Days set to 0, Weeks to 5, Months to 13, and Years to 3. The following image illustrates the current settings.

    The following table describes the backups that will be retained based on this scenario.

    Backup PeriodRetention SettingBackups Retained (by date)Unique Backups
    Most Recent3

    10/29, 10/28, 10/27


    10/29*, 10/24, 10/17, 10/10, 10/3

    Months1310/29*, 9/30, 8/31, 7/31, 6/30, 5/31, 4/30, 3/31, 2/28, 1/31, 12/31/09, 11/30/09, 10/31/0912
    Years310/29/2010*, 12/31/2009*, 12/31/20081
    Total Backups Retained20

    * Backup already retained; not unique.

    Retention Policy Queue Depth

    The Retention Process deletes virtual machines that fall outside the retention period. These deletes are processed daily, when backups are not running. Deletes to be processed are first added to a utility queue, then each delete takes place. In some scenarios, if the delete queue grows too high, the retention policy can fall behind, resulting in additional space requirements on the backup data store. You can monitor the deletes pending by viewing the email report after each backup. In the Job Summary, the Retention Policy Queue Depth represents the total number of deletes pending at any time. The number of deletes pending daily should never be much higher than the total number of virtual disks in a daily backup job - environments do change over time, though, so the number of deletes processed may not always match the number of virtual disks that were backed up on a given day. If you notice consistently high Retention queues, you have a few options. For details, see Retention and Post Processing Queue Depths.

Was this article helpful?
0 out of 0 found this helpful
Have more questions? Contact us