Data Storage Swap Defragmentation Without Data Movement
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Solution Overview
Problem
Logical fragmentation in data storage devices leads to increased processing overhead and reduced performance, as non-contiguous logical addresses require multiple I/O commands, causing fragmentation that existing defragmentation methods like copying data to new addresses can exacerbate by requiring additional space and increasing metadata tracking complexity.
Innovation Solution
A swap operation is executed within the data storage device to reassociate logical addresses between files without moving data, reducing fragmentation by swapping the logical addresses associated with data fragments of different files, thereby maintaining existing physical addresses and minimizing overhead.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If data is copied to new addresses to reduce fragmentation, then logical fragmentation is reduced, but additional free space is required and metadata tracking complexity increases
Solution Approach 1:
The patent uses a copy operation to create a mapping between the first logical address range and the second logical address range. This copying mechanism allows the system to reduce fragmentation by redirecting data references without physically moving data, thereby avoiding the need for additional free space while managing metadata through the copy mapping structure.
Solution Approach 2:
The patent introduces a copy mapping as an intermediary structure between the original logical address mapping and the new logical address mapping. This intermediary copy mapping enables the system to track and manage the relationship between old and new addresses, reducing metadata tracking complexity by consolidating the mapping information in a single structure rather than requiring multiple separate metadata entries.
2Reliability
If data is copied to new addresses to reduce fragmentation, then logical fragmentation is reduced, but processing overhead increases
Solution Approach 1:
The patent performs the copy mapping operation in advance during the defragmentation process, establishing the relationship between old and new logical addresses before data is actually accessed. This preliminary action allows subsequent data reads and writes to use the optimized address mapping without requiring repeated copy operations, thereby reducing processing overhead during normal operation.
Solution Approach 2:
By using a copy mapping that creates a reference relationship between the first and second logical address ranges, the system can redirect data access without physically copying data multiple times. This copying mechanism at the address mapping level rather than at the data level significantly reduces processing overhead while achieving fragmentation reduction.
3Reliability
If traditional defragmentation methods are used, then fragmentation is reduced, but holes are left in address space and additional free space is consumed
Solution Approach 1:
The patent uses a copy mapping that creates a reference relationship between the first logical address range and the second logical address range. This copying mechanism allows the system to redirect data references without physically moving data, thereby avoiding the need for additional free space while managing metadata through the copy mapping structure.
Solution Approach 2:
Instead of physically moving data to new locations and creating holes in the address space, the patent inverts the approach by creating a mapping that redirects references to the same physical locations. This inversion eliminates the need to allocate additional free space for relocated data while still achieving fragmentation reduction through the logical address remapping.
Data Source
AI summary
A data storage device stores files in its memory. The files may be logically fragmented in that various parts of a given file may be located in non-continuous logical addresses, which can be disadvantageous. The host can send a request to the data storage device to reduce such logical fragmentation. For example, the host can send a swap command to the data storage device, in response to which the data storage device swaps the logical addresses of data fragments of two different files. This results in the logical address of one or both of the data fragments being continuous with the logical address of another data fragment of the same file. This logical address swap can take place without physically moving the data in the memory.