Retention defines the rules for retaining your backed-up snapshots within storage. Use retention period to define the duration for which you want to retain your historic snapshots.
The main 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 period for customers' financial records are different from facilities inventory records.
How Phoenix uses retention settings?
Phoenix follows the Grandfather-Father-Son (GFS) retention model. You must define the duration to retain snapshots.
- Daily snapshots - Phoenix retains all the snapshots that are created for the number of days specified in Daily snapshots.
- Weekly snapshots (Son) - Number of weekly snapshots that Phoenix should retain. Phoenix treats the latest snapshot in the week as the weekly snapshot.
- Monthly snapshots (Father) - Number of monthly snapshots that Phoenix should retain. Phoenix treats the latest snapshot in the month as the monthly snapshot.
- Yearly snapshots (Grandfather) - Number of yearly snapshots that Phoenix should retain. Phoenix treats the latest snapshot in the year as the yearly snapshot.
Example
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Let us assume, if you have specified below 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, Phoenix performs a daily backup at 22:00 hrs in your environment and today’s date is September 15th, 14:00 hrs.
Based on the retention period, Phoenix retains snapshots as follows,
- 14 Daily snapshots - Server A has been successfully backed up for the last 14 days. As per 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 14th September, 11:45 PM UTC, all the snapshots for 31st August are deleted.
Note: If you have configured Phoenix to back up your server multiple times within a day, Phoenix retains all the snapshots for 14 days.
- 4 Weekly snapshots are retained for
- 11th September
- 4th September
- 28th August
- 21st August
Phoenix deletes the oldest weekly snapshot, that is, 21st August snapshot on completion of 4 weeks period on 18th September.
- 12 Monthly snapshots are retained for
- 31st August
- 31st July
- 30th June
- 31st May
- 30th April
- 31st March
- 29th February
- 31st January
- 31st December, 2015
- 30th November, 2015
- 31st October, 2015
- 30th September, 2015
Phoenix deletes the oldest monthly snapshot, that is, 30th September, 2015 snapshot on completion of 12 months period on 30th September, 2016.
- 5 Yearly snapshots are retained for
- 31st December 2015
- 31st December 2014
- 31st December, 2013
- 31st December, 2012
- 31st December, 2011
Phoenix deletes the oldest yearly snapshot, that is, 31st December, 2011 snapshot on completion of 5 years period on 31st December, 2016.
Note: The exact backup policy configuration depends on the data needs of your File servers and your organization's policies. If you must, you can update backup policies frequently. To create backup policies that are best-suited for your environment, ensure that you are aware of your data needs and organizational policies. If you require assistance, contact Druva Support.