SSD Combo Page Metadata Map Structure
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Solution Overview
Problem
The large metadata map structures in solid-state drives (SSDs) become difficult to load during initialization and update during operation, requiring significant resources as they grow with increasing data storage capacities, making them inefficient to manage and update.
Innovation Solution
Implementing a multi-level metadata map structure using combined 'combo pages' that store both first and second level map entries in the same physical area of memory, with a combo page footer describing the second level entries, allowing for efficient retrieval and distribution across different die/channel combinations to reduce the size of the maps and local memory requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If metadata map structures are stored separately in different memory locations, then address translation can be performed, but the size of local memory required to load map data increases significantly
Solution Approach 1:
The patent combines first level map entries and second level map entries into a single combined page structure stored in non-volatile memory. The footer contains first level entries while the data portion contains second level entries, allowing both levels to be loaded into local memory simultaneously as one unit, reducing total memory requirements while maintaining efficient address translation capability
Solution Approach 2:
The metadata map is segmented into a footer portion and a data portion, where the footer contains first level map entries that index into the data portion containing second level map entries. This segmentation allows the system to load only relevant portions of the map structure into local memory, reducing the memory burden while preserving full address translation functionality
2Adaptability or versatility
If multi-level map structures are used to manage large data storage capacities, then address translation capability is maintained, but the complexity of loading and updating maps during operation increases
Solution Approach 1:
By merging first and second level map entries into a single combined page with a unified structure, the patent simplifies map management operations. The controller can load and update entire combined pages as atomic units rather than managing separate map structures, reducing the operational complexity while maintaining multi-level address translation capability
Solution Approach 2:
The combined page structure is pre-organized in non-volatile memory with the footer containing first level entries that directly index into the data portion containing second level entries. This preliminary organization allows the controller to efficiently load pre-configured map pages into local memory without complex runtime assembly operations, reducing operational complexity
3Productivity
If first and second level map entries are stored in separate pages, then memory organization is simplified, but retrieval efficiency decreases due to sequential access requirements
Solution Approach 1:
The patent merges first and second level map entries into the same combined page structure, enabling the controller to retrieve both levels of mapping information in a single memory operation. The footer and data portion are loaded together into local memory, eliminating sequential access delays and significantly improving metadata retrieval efficiency while maintaining organized memory structure through the indexed entry system
Data Source
AI summary
Apparatus and method for managing metadata in a data storage device such as a solid-state drive (SSD). The metadata are stored in combined (combo) pages in a non-volatile memory (NVM) each having first and second level map entries. The second level map entries provide a logical-to-physical address translation layer for user data blocks stored to the NVM, and the first level map entries describe the second level map entries in the combo page. A global map structure is accessed to identify a selected combo page in the NVM associated with a pending access command. The first and second level map entries are retrieved from the combo page, and the second level map entries are used to identify a target location for the transfer of user data blocks to or from the NVM.