Virtual Machine Snapshot TTL Retention Policy
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Solution Overview
Problem
Virtual machine snapshots consume valuable storage space and impact performance due to the lack of effective retention policies, leading to unnecessary storage of unneeded snapshots and slow I/O operations as systems accumulate snapshots over time.
Innovation Solution
Implementing a time-to-live (TTL) parameter for virtual machine snapshots, where the virtualization manager automatically deletes snapshots based on their TTL value, using scheduled jobs, triggers, and sorted priority queues to manage snapshot expiration and storage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If virtual machine snapshots are retained indefinitely for recovery purposes, then system reliability is improved, but storage space is wasted and I/O performance deteriorates due to accumulating unneeded snapshots
Solution Approach 1:
The patent applies parameter changes by introducing a TTL (time-to-live) parameter that dynamically determines snapshot retention duration. Snapshots are automatically deleted after their TTL expires, transforming the static indefinite retention policy into a dynamic time-based parameter that balances reliability needs with storage efficiency.
Solution Approach 2:
The patent implements preliminary action by setting expiration timestamps and TTL values at the moment of snapshot creation. This predetermined retention policy allows the system to automatically manage snapshot lifecycles without continuous intervention, ensuring snapshots are retained long enough for recovery purposes but automatically removed when no longer needed.
2Reliability
If multiple snapshots are accumulated over time for recovery purposes, then system reliability is improved, but I/O operation speed deteriorates due to increased access overhead
Solution Approach 1:
The patent uses parameter changes by implementing a TTL-based retention policy that automatically removes expired snapshots. This parameter-driven approach ensures that only recently created snapshots within their TTL window are retained, reducing the number of snapshots the system must scan and access during I/O operations while maintaining recovery capability for recent states.
Solution Approach 2:
The patent applies partial action by retaining only the necessary portion of snapshots - specifically those within their TTL window - rather than keeping all historical snapshots. This selective retention strategy maintains sufficient recovery capability for recent failures while minimizing the overhead of managing and accessing excessive old snapshots.
3Quantity of substance
If automatic snapshot deletion is implemented to free storage space, then storage efficiency is improved, but system complexity increases due to retention policy management
Solution Approach 1:
The patent implements self-service by enabling snapshots to automatically manage their own lifecycles through embedded TTL parameters and expiration timestamps. The virtualization manager simply enforces these pre-set parameters, allowing snapshots to self-delete when expired without requiring complex external retention policy management or manual intervention.
Solution Approach 2:
The patent applies preliminary action by pre-configuring TTL values and expiration timestamps at snapshot creation time. This upfront parameter setting simplifies subsequent management, as the virtualization manager only needs to compare current time against pre-calculated expiration timestamps rather than managing complex retention policies dynamically.
4Reliability
If snapshots are retained without expiration to ensure recovery capability, then reliability is improved, but productivity decreases due to slower I/O operations
Solution Approach 1:
The patent applies parameter changes by introducing time-based TTL parameters that automatically expire snapshots after a predetermined duration. This transforms the retention policy from indefinite to time-limited, ensuring recovery capability is maintained for the necessary period while automatically removing old snapshots that degrade I/O performance through increased access overhead.
Data Source
AI summary
Systems and methods for enforcing retention policies with respect to virtual machine snapshots are disclosed. In one implementation, a method may include identifying, by a virtualization manager, a snapshot of a virtual machine hosted by a host computer system. The method further includes retrieving, from metadata associated with the snapshot, a value of a time to live (TTL) parameter associated with the snapshot. The method also includes responsive to determining that the value of the TTL parameter satisfies a threshold criterion, deleting the snapshot.