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Druva Documentation

About retention for backup policies

Retention defines the rules for retaining your backup snapshots on the Druva CloudRanger console. Use retention period to define the duration for which you want to retain your historic snapshots. The primary objective of retention is to keep important data for future access, depending on how critical it is, and how often it will be required. Retention also ensures that snapshots that are no longer required are cleaned from your storage periodically, resulting in less storage utilization and costs.

Retention should consider the value of your data, as well as the legal requirements that you might need to adhere to. This means that different types of data will be retained for different durations. For example, a bank's retention settings for customers' financial records are different from the facilities' inventory records.

The important factors to consider while defining a retention period are as follows:

  • Legal requirements
  • Storage costs

  • Type of data

What should you know about retention? 

  • Any changes that you make to the existing retention policies will be applied to all the new as well as the existing snapshots.

  • Retention periods are applicable for snapshots that reside in the Druva CloudRanger console.

  • You will have to enter appropriate retention settings to retain snapshots.

  • If you are registering the server under default organization, CloudRanger provides a default backup policy with the following retention settings:

    • All snapshots: 1 day

    • Weekly revisions: 2 weeks

    • Monthly revisions: 1  month

    • Yearly revisions: 3  years

  • Druva CloudRanger runs a retention expiration algorithm to delete the snapshots that have crossed the expiration period.

  • Druva CloudRanger follows the Gregorian calendar for tracking days.

  • For daily snapshots, Druva CloudRanger considers midnight as the end of a day.

  • For weekly snapshots, Druva CloudRanger considers midnight of Sunday as the end of the week.

  • For monthly snapshots, Druva CloudRanger considers midnight of the last day of the month as the end of the month.

  • For yearly snapshots, Druva CloudRanger considers the midnight of the last day of the year as the end of the year.

  • Snapshot name displayed on the CloudRanger Management Console is snapshot creation time as per the policy time zone, on which the backup occurred. CloudRanger considers the time zone of the policy for retaining the snapshots based on the retention settings.

How Druva CloudRanger uses retention settings 

DruvaCloudRanger follows the Grandfather-Father-Son (GFS) retention model. You must define the duration to retain snapshots. Here's the description of daily, weekly, monthly, and yearly snapshots:

  • Daily snapshots: Druva CloudRanger retains all the snapshots that are created for the number of days specified in Daily snapshots.

  • Weekly snapshots (Son): Number of weekly snapshots that Druva CloudRanger should retain. Druva CloudRanger treats the latest snapshot in the week as the weekly snapshot.

  • Monthly snapshots (Father): Number of monthly snapshots that Druva CloudRanger should retain. Druva CloudRanger treats the latest snapshot in the month as the monthly snapshot.

  • Yearly snapshots (Grandfather): Number of yearly snapshots that Druva CloudRanger should retain. Druva CloudRanger treats the latest snapshot in the year as the yearly snapshot.

Example

Following is the calendar for September 2016.

Mon

Tue

Wed

Thu

Fri

Sat

Sun

 

 

 

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

 

 

Let us assume that you have specified the following configuration in your retention settings of the backup policy:

  • Keep all snapshots for 14 days

  • Keep weekly revisions for  4 weeks

  • Keep monthly revisions for 12 months

  • Keep yearly revisions for 5 years

Assume that Druva CloudRanger performs a daily backup at 22:00 hrs in your environment and today’s date is September 15, 14:00 hrs.

Based on the retention period, Druva CloudRanger retains snapshots as follows,

  • 14 Daily snapshots - Server A has been successfully backed up for the last 14 days. Based on the configuration, all the snapshots that are generated as part of backups are retained for 14th, 13th, 12th, 11th, 10th, 9th, 8th, 7th, 6th, 5th, 4th,  3rd, 2nd, and 1st September. On September 14, 11:45 PM UTC, all the snapshots for August 31 are deleted.

Note: If you have configured Druva CloudRanger to back up multiple times within a day, Druva CloudRanger retains all the snapshots for 14 days.

  • 4 Weekly snapshots are retained for

    • September 11

    • September 4

    • August 28

    • August 21

Druva CloudRanger deletes the oldest weekly snapshot, that is, the August 21 snapshot on completion of 4 weeks period on September 18.

  • 12 monthly snapshots are retained for

    • August 31

    • July 31

    • June 30

    • May 31

    • April 30

    • March 31

    • February 29

    • January 31

    • December 31, 2015

    • November 30, 2015

    • October 31, 2015

    • September 30, 2015

Druva Cloudranger deletes the oldest monthly snapshot, that is, September 30, 2015 snapshot on completion of a 12-month period on September 30, 2016.

  • 5 yearly snapshots are retained for

    • December 31, 2015

    • December 31, 2014

    • December 31, 2013

    • December 31, 2012

    • December 31, 2011

Druva CloudRanger deletes the oldest yearly snapshot, that is, December 31, 2011 snapshot on completion of 5 years period on December 31, 2016. is accustomed to another, similar product, or an older version of a feature.

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