Buffer Tree ID Segmentation for Storage Volume Hierarchy
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Solution Overview
Problem
In storage systems, the potential for overlapping data block context signatures among related volumes, such as parents and clones, leads to data ID aliasing, making it difficult to detect incorrect data blocks and correct them, especially in cases of lost writes or data re-allocation.
Innovation Solution
Assigning unique buffer tree identifiers (bufftree IDs) to volumes in the storage volume hierarchy allows clone volumes to determine the ownership of data blocks, ensuring that only correctly written data blocks are confirmed, thereby preventing data ID aliasing and allowing accurate identification of incorrect data blocks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If clone volumes inherit the bufftree ID of parent volumes to read shared data blocks, then data block access is enabled without triggering context mismatch, but data ID aliasing occurs making it difficult to detect incorrect data blocks
Solution Approach 1:
The patent segments the bufftree ID into two components: a parent bufftree ID (inherited by clones) and a clone-specific bufftree ID (assigned uniquely to each clone volume). This segmentation allows clone volumes to access parent data blocks through the parent bufftree ID while maintaining unique identification through the clone-specific bufftree ID, preventing data ID aliasing between clones and parents.
Solution Approach 2:
The patent introduces a mapping structure as an intermediary between the parent volume and clone volumes. This mapping structure stores the relationship between parent bufftree IDs and clone-specific bufftree IDs, enabling the system to resolve context signatures correctly when accessing data blocks. The mapping structure acts as a mediator that translates between the shared parent identifier and the unique clone identifier.
2Quantity of substance
If multiple volumes share the same bufftree ID, then storage space is optimized through sharing, but overlapping context signatures cause data ID aliasing and lost write detection failures
Solution Approach 1:
The patent segments the identification space by separating the shared parent bufftree ID from the unique clone-specific bufftree ID. This allows multiple volumes to share the same parent bufftree ID (optimizing storage space) while maintaining unique context signatures through the clone-specific component (preventing aliasing).
Solution Approach 2:
The patent adds an additional dimension to the bufftree ID structure by introducing the clone-specific bufftree ID as a second level of identification. This dimensional expansion allows the system to distinguish between different clone volumes that share the same parent bufftree ID, resolving the aliasing problem while maintaining space efficiency.
3Reliability
If context information is stored with data blocks to confirm correctness, then data integrity is improved, but the complexity of detecting and recovering from lost writes increases
Solution Approach 1:
The patent segments the context information into distinct components: parent bufftree ID, clone-specific bufftree ID, data ID, and write time. This segmentation allows the system to efficiently verify data integrity by checking only the relevant components against the expected values, reducing the complexity of lost write detection while maintaining comprehensive integrity checking.
Solution Approach 2:
The patent implements a feedback mechanism where the stored context information (bufftree ID and write time) is compared against the expected context when reading data blocks. This feedback loop enables automatic detection of lost writes and incorrect data blocks, allowing the system to recover or report errors without manual intervention, thus managing complexity through automated verification.
Data Source
AI summary
A technique uniquely identifies block context signatures in a storage volume hierarchy of a storage system. In particular, the technique assigns unique volume identifiers (“IDs,” e.g., buffer tree or “bufftree” IDs) to volumes of the storage volume hierarchy, and allows clone volumes to determine that data blocks belong to an appropriate ancestor volume (e.g., and were written by the ancestor volume prior to creation of the clone). In this manner, the novel technique may uniquely identify and accurately determine whether an accessed data block is a correct data block (e.g., alleviating occurrences of data ID aliasing).