Nonvolatile Memory Management Device Wear Leveling
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Solution Overview
Problem
Existing nonvolatile memory management devices face challenges in accurately managing the number of rewrites across different areas, such as pages and cache lines, due to the large memory requirements for precise wear leveling control, which affects the longevity of storage class memories.
Innovation Solution
A management device that includes a counter storage unit, a management information storage unit, and an update unit to store and update counter values and management information for each area, allowing for efficient wear leveling by distinguishing between written and unwritten states within each area, thereby reducing storage capacity needs and ensuring accurate rewrite management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the number of rewrites is managed in units of byte or cache memory to achieve accurate wear leveling control, then measurement precision is improved, but device complexity increases due to the need for very large memory tables
Solution Approach 1:
The patent segments the storage space into multiple regions (first space, second space, third space) with different granularity levels. The first space is divided into pages, each page into cache lines, and each cache line into bytes. Different wear leveling strategies are applied to different segments, allowing precise tracking where needed while reducing overall memory requirements through hierarchical management.
Solution Approach 2:
The patent introduces a hierarchical dimension to the wear leveling management structure. Instead of a flat table tracking every byte, the system creates multiple levels of aggregation (byte-level within cache lines, cache line-level within pages, page-level within regions), adding a dimensional hierarchy that reduces the complexity of the management table while preserving measurement precision through selective tracking.
2Device complexity
If the number of rewrites is managed only in units of page to reduce memory requirements, then device complexity is reduced, but measurement precision deteriorates as the system cannot distinguish between writes to different bytes or cache lines within a page
Solution Approach 1:
Each page is segmented into multiple cache lines, and each cache line is further segmented into bytes. The management table tracks rewrite counts at the cache line level rather than the byte level, providing a middle ground that reduces memory requirements while maintaining sufficient precision for wear leveling control.
Solution Approach 2:
The system applies partial tracking by monitoring rewrite counts at the cache line level rather than the finer byte level. This partial action provides adequate precision for wear leveling purposes without the excessive memory requirements of full byte-level tracking, achieving the desired balance between precision and complexity.
Data Source
AI summary
According to an embodiment, a management device includes a counter storage unit, a first management information storage unit, and an update unit. The first management information storage unit stores a first management table capable of storing first management information about each of a predetermined number of first areas. The first management information indicates whether each second area included in a corresponding first area has data written therein. In response to writing of first data into the nonvolatile memory, when a state of a target second area indicated in the first management information about a target first area is an unwritten state, the update unit changes the state of the target second area to a written state; while when the state of the target second area indicated in the first management information is the written state, the update unit updates the counter value for the target first area.