Snapshot Deletion via Flag Bit Aggregation
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Solution Overview
Problem
Current methods for deleting snapshots in storage systems are time-consuming due to the need for individual read and write operations on metadata for each snapshot, which slows down the release of storage space when multiple snapshots need to be deleted.
Innovation Solution
A method that sets flag bits for snapshots sharing a single data block to a predetermined state, allowing for concurrent deletion and reducing the need for multiple metadata operations, by updating weights and releasing data blocks efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple snapshots are deleted one by one, then each snapshot can be deleted individually, but the storage space cannot be released rapidly due to time consumption
Solution Approach 1:
The patent merges multiple snapshot deletion operations into a single atomic operation. When multiple snapshots point to the same data block, the system sets flag bits for all snapshots simultaneously and performs a single weight update operation instead of executing multiple separate read-modify-write cycles for each snapshot individually.
Solution Approach 2:
The patent performs preliminary identification and flag setting before the actual deletion. By first determining which snapshots share the same data block and setting their flag bits to the first state, the system prepares for a batch weight update operation that can release storage space for all snapshots simultaneously without requiring sequential metadata operations.
2Reliability
If read and write operations are performed for each snapshot metadata, then snapshot deletion can be completed, but a large quantity of time is consumed
Solution Approach 1:
The patent combines multiple metadata read-write operations into a single atomic weight update operation. By setting flag bits for all snapshots sharing a data block and then performing one consolidated weight update, the system maintains deletion completeness while reducing metadata operations from multiple sequential reads/writes to a single operation.
Solution Approach 2:
The patent enables the system to track and manage snapshot deletion internally through flag bits stored in metadata. The flag bits automatically identify which snapshots share the same data block, allowing the system to perform self-organized batch deletion without requiring external intervention or multiple separate metadata operations for each snapshot.
3Productivity
If flag bits are set for snapshots sharing the same data block, then concurrent deletion can occur, but additional metadata management is required
Solution Approach 1:
The patent uses flag bits as a self-managing mechanism within existing metadata structures. The flag bits are set during the normal metadata read operation and automatically trigger the batch deletion process when weight update is needed, eliminating the need for separate complex management systems while enabling concurrent deletion and rapid storage space release.
Data Source
AI summary
Techniques delete snapshots. The techniques involve: in response to a data block to which a plurality of snapshots of a file to be deleted point being shared, determining whether a physical address of the data block to which the plurality of snapshots to be deleted point is the same as a target physical address of a data block to which a target snapshot of the file points. The techniques further involve: in response to the physical address of the data block to which the plurality of snapshots to be deleted point being the same as the target physical address, setting flag bits associated with the plurality of snapshots to be deleted to a first state. The techniques further involve: in response to detecting the first state, updating a target weight with a sum of weights of the plurality of snapshots to be deleted (e.g., respective quotas).