Data Segment Ownership Tracking via Segmented Counters
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Solution Overview
Problem
Data migration in storage systems faces challenges in determining available storage space and space recovery, especially due to deduplication techniques that complicate tracking of exclusively owned data blocks, as existing methods like reference counting cannot distinguish between exclusive and shared ownership.
Innovation Solution
A method involving multiple counts to determine data segment ownership, including a first count for identifying storage entities, a second count derived from key values, and a third count for the number of references, allowing for accurate determination of exclusive ownership based on these counts and key values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If reference counting is used to track data blocks, then the number of references can be determined, but it cannot distinguish between exclusive and shared ownership
Solution Approach 1:
The patent segments the reference counting mechanism into multiple independent counters: a first counter for total reference count, a second counter for exclusive ownership tracking, and a third counter for shared reference tracking. This segmentation allows the system to simultaneously track both the total number of references and the specific ownership status, resolving the contradiction by providing detailed ownership information that a single reference count cannot provide.
2Quantity of substance
If data deduplication is implemented, then storage space efficiency is improved, but tracking exclusively owned data blocks becomes complicated
Solution Approach 1:
The patent divides the ownership tracking function into separate counter mechanisms that work independently alongside the deduplication process. The first counter tracks total references, the second counter tracks exclusive ownership, and the third counter tracks shared references. This segmentation simplifies the tracking complexity by providing clear, separate metrics for each ownership state, making it easier to manage deduplicated data while maintaining accurate ownership information.
Solution Approach 2:
The patent implements feedback mechanisms where the counters continuously update based on data block reference changes. When data blocks are deduplicated or migrated, the counters automatically adjust to reflect the current ownership state. This feedback loop ensures that storage space accounting remains accurate despite the complexity of deduplication operations, resolving the contradiction between space efficiency and tracking complexity.
3Adaptability or versatility
If volume family data migration is performed, then data protection and mobility are improved, but determining available storage space and space recovery becomes difficult
Solution Approach 1:
The patent segments storage space accounting into distinct components: space occupied by exclusively owned data blocks (tracked by the second counter) and space occupied by shared data blocks (tracked by the third counter). This segmentation enables precise measurement of available storage space and space recovery potential during volume family data migration, resolving the contradiction by providing accurate space metrics that support both data mobility and space management.
Data Source
AI summary
Techniques are disclosed for determining ownership of a data segment. The techniques include providing a data segment in a data storage appliance that facilitates multiple references of the data segment by one or more storage entities. The techniques also include maintaining a plurality of counts in connection with the data segment, the plurality of counts comprising (i) a first count representing a sum of first values that identify the respective storage entities associated with each reference of the data segment, (ii) a second count representing a sum of second values that derive from key values of the respective storage entities associated with each reference of the data segment, and (iii) a third count representing a number of references of the data segment by the respective storage entities. The techniques also include determining whether the said storage entity exclusively owns the data segment based on the plurality of counts and a key value of one of the respective storage entities.