Bit-Level Indirection Defragmentation for Storage
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Solution Overview
Problem
Existing logical defragmentation methods for storage devices often result in premature filling of storage space due to zero-padding, leading to compromised performance, especially in full-volume random writes and resource-constrained environments.
Innovation Solution
A method where a controller groups sequential logical block addresses into groups with equal numbers, determines which groups reference valid data, and uses a bit-level indirection table to track these groups, allowing only padded groups to be written sequentially, thereby avoiding unnecessary zero-padding and optimizing resource usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If traditional logical defragmentation is performed with zero-padding for all non-valid logical block addresses, then logical continuity is achieved, but storage space is prematurely filled and performance is compromised
Solution Approach 1:
The patent segments the storage device into multiple logical spans, where each span is independently defragmented. This allows the system to maintain logical continuity within each span while avoiding the need to pad entire volumes with zeros, thereby conserving storage space and preventing premature filling.
Solution Approach 2:
The patent applies zero-padding selectively at the logical span level rather than uniformly across the entire storage volume. Each logical span is evaluated independently, and padding is applied only where necessary to maintain logical continuity within that specific span, optimizing both logical stability and space utilization.
2Speed
If zero-padding is applied to maintain logical block address continuity, then sequential access is enabled, but storage capacity is reduced due to consumed padding space
Solution Approach 1:
By dividing the storage device into multiple logical spans and independently managing defragmentation for each span, the system achieves sequential access within spans without requiring padding across the entire volume. This segmentation enables efficient sequential access while preserving overall storage capacity.
Solution Approach 2:
The patent applies zero-padding partially, only to the extent necessary within each logical span to achieve logical continuity. This partial action approach provides sufficient sequential access capability while avoiding the excessive padding that would consume unnecessary storage capacity.
3Productivity
If full-volume defragmentation is performed, then overall storage performance is improved, but resource consumption increases and premature filling occurs
Solution Approach 1:
The patent divides the storage device into multiple logical spans and performs defragmentation independently on each span. This segmentation reduces the overall resource consumption compared to full-volume defragmentation while maintaining storage performance through systematic processing of smaller, manageable units.
Solution Approach 2:
The system can process logical spans in a periodic or iterative manner, defragmenting one span at a time rather than processing the entire volume simultaneously. This periodic approach reduces peak resource consumption and avoids premature filling by spreading the defragmentation workload across multiple processing cycles.
Data Source
AI summary
In general, techniques are described for logical defragmenting of a storage device. A controller of a storage device groups sequential logical block addresses of a logical span into a plurality of groups. Each group includes a same number of logical block addresses, and each logical block address references a physical location of a physical block on the storage device. For each group, the controller determines whether at least one logical block address references a physical location of a physical block that includes valid data. Responsive to the at least one logical block address referencing valid data, the controller stores a first value to a field of a bit-level indirection table. The bit-level indirection table includes a number of fields equal to a number of groups of sequential logical block addresses. Responsive none of the logical block addresses referencing valid data, the controller stores a second value to the field.