Flash Registry Write Leveling for NAND Pointer Update Overhead
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Solution Overview
Problem
Conventional data storage methods using tree-based data structures on NAND flash media are inefficient due to the limited number of writes supported, as they require frequent updates to all pointer layers, which is not suitable for NAND flash devices that support fewer writes than reads.
Innovation Solution
A data structure that trades writes for reads, incorporating caching and write leveling, utilizing a flash registry with a shadow registry to minimize write operations and optimize read performance, suitable for NAND flash storage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If tree-based data structures are used for data storage on NAND flash media, then data structure functionality is achieved, but write efficiency deteriorates due to frequent updates to all pointer layers
Solution Approach 1:
The patent introduces a shadow registry that pre-stores backup copies of registry entries before actual writes occur. This preliminary action allows the system to prepare for future write operations by maintaining backup versions, thereby reducing the need for frequent full pointer layer updates when changes occur.
Solution Approach 2:
The patent creates a shadow registry that is a copy of the main registry structure. This copy stores redundant information that can be used instead of updating the original registry pointers, thereby reducing write amplification and improving write efficiency by avoiding frequent updates to all pointer layers.
2Reliability
If traditional tree-based data structures are used, then data storage functionality is provided, but reliability deteriorates due to limited number of writes supported by NAND flash
Solution Approach 1:
The shadow registry performs preliminary actions by storing backup copies of registry entries before they are overwritten. This ensures that even if the main registry is overwritten multiple times (up to the NAND flash limit), the system can recover using the shadow registry backups, thereby improving reliability without requiring additional write operations to the flash medium.
Solution Approach 2:
By maintaining a shadow registry as a copy of the main registry, the system creates a safety mechanism that preserves historical versions of registry data. This copying approach protects against data loss from excessive writes to NAND flash, improving reliability while the shadow registry itself does not consume additional flash write operations.
3Duration of action of stationary object
If write operations are minimized, then NAND flash lifespan is extended, but read performance may deteriorate due to caching requirements
Solution Approach 1:
The shadow registry creates a copy of registry data that can be read without performing writes to the NAND flash medium. This allows the system to maintain fast read performance by serving requests from the shadow registry cache while extending flash lifespan by minimizing actual write operations to the flash storage.
Solution Approach 2:
The shadow registry acts as an intermediary between read operations and the NAND flash medium. It provides cached copies of registry data that can be read quickly without triggering writes to flash, thereby maintaining read performance while preserving flash lifespan by reducing direct read-access-to-flash operations.
Data Source
AI summary
A plurality of computing devices are communicatively coupled to each other via a network, and each of the plurality of computing devices is operably coupled to one or more of a plurality of storage devices. A plurality of failure resilient address spaces are distributed across the plurality of storage devices such that each of the plurality of failure resilient address spaces spans a plurality of the storage devices. Each computing device is operable to maintain a two-level registry that records changes in the memory. When data is read from memory, recent changes to the data may be applied according to one or more corresponding registry blocks. Thus, the two-level registry enables the plurality of computing devices to postpone and/or consolidate writes to memory (e.g., non-volatile flash drives).