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Title
Understanding Retention Policy and Rollup -
Description
This article explains how the rollup process in Rapid Recovery enforces the retention policy for a protected machine.
When protecting data with Rapid Recovery, frequent backup snapshots are taken based on the protection policy. These snapshots are saved to the repository defined by the Core, where they are deduplicated before being committed. Each snapshot (recovery point) represents the state of the agent machine at the time it was taken. As more recovery points are created, they can quickly consume storage resources. The rollup process helps conserve resources by consolidating older recovery points into less granular recovery points. This article details how the retention policy influences the rollup process.
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Resolution
Retention Policy Overview
The retention policy defines how long recovery points are retained in their original form and when they should be rolled up into less granular recovery points. Administrators can set a default retention policy when configuring the Core, or they can customize it for each protected agent.
- Primary Retention Setting: Specifies how long all snapshots should be retained in their original form.
- Rollup Rules: Up to five rollup rules can be configured. Each rule defines the time period (hour, day, week, etc.) and the duration for which recovery points are rolled up into fewer points, and how long those rolled-up points are retained.
For more details on retention policies and rollup, refer to the the Rapid Recovery User Guide, Managing aging data.
Applying Retention Policies
When adding a machine to protection, administrators can either apply the Core’s default retention policy or create a custom policy for that agent. For instructions, refer to:
Rollup Process
The rollup process occurs automatically, typically during the nightly job (which runs by default at midnight, but can be adjusted). The system checks the age of recovery points against the retention policy, and when recovery points exceed the policy’s age limits, they are consolidated into fewer recovery points.
Recovery points initially persist in their original form as dictated by the Primary Retention Setting (e.g., “Keep all recovery points for 3 days”). Once they exceed this timeframe, rollup rules are applied.
Impact on Recovery Point Size:
It is important to note that after rollup, recovery points may increase in size. During the rollup process, the system consolidates the most recent versions of each block from multiple recovery points into a single recovery point. As a result, the newly merged recovery point might be larger than the individual points it replaces. This increase happens because the consolidated recovery point retains all the relevant data from the merged points, ensuring that the recovery process is still comprehensive despite the rollup.
Example of Rollup Process - Putting it all Together
The rollup process in Rapid Recovery is essential to ensure efficient use of storage resources over time. As data ages, older recovery points are consolidated into fewer, less granular recovery points, following the rules set in the retention policy. The diagram below illustrates how the rollup process works in a simplified manner:- Retention Policy establishes rollup timing (hourly, daily, weekly, etc.).
- Granularity cells are filled as per the retention policy, and as they reach capacity, recovery points are “rolled up” to the next larger granularity cell (Hourly to Daily, Daily to Weekly, etc.).
- Meta Data is merged during the rollup, while Data (the actual repository records) remains.
- Deferred Delete is used to remove unnecessary data outside the retention policy.
Example: Assuming a base is taken, and one recovery point is retained per day for 7 days:
- Days 1 to 7: Data and Meta Data are snapped daily.
- On Day 8: The 7 recovery point bucket is full, and recovery points from Days 1 and 2 are merged (rolled up).
- On Day 9: The process continues with Day 3 being rolled up with Days 1 and 2, reducing the number of recovery points.
- By Day 14: The 7-day policy is met, and a weekly rollup occurs, merging the daily recovery points into a less granular weekly recovery point.
This visual helps illustrate how recovery points accumulate and are then rolled up over time, reducing their granularity while maintaining the ability to restore data efficiently.Nightly Rollulp Job
The rollup process typically runs during the nightly job. By default, this job is scheduled for midnight, but your organization can adjust this timing. For more information on adjusting the nightly job time, refer to the Rapid Recovery User Guide, Configuring nightly jobs for the Core.
Conclusion
Over time, as data ages, the rollup process reduces the number of recovery points by consolidating them into fewer, less granular recovery points. This continues until the data “ages out” as defined by the retention policy. Rollup is essential to balance storage efficiency while retaining the ability to recover data over time.
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