Nonvolatile Buffer Cache State Management for Data Consistency
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Solution Overview
Problem
Conventional storage management techniques face challenges in managing nonvolatile buffer caches and mass storage effectively, leading to reduced performance and lifespan due to overhead from management tasks, and journaling file systems are not easily applicable to cloud storage systems, causing increased network access costs and performance reductions.
Innovation Solution
An integrated nonvolatile memory control subsystem that includes a nonvolatile buffer cache, a journal area, and storage, with an integrated memory control unit managing states to maintain authentic original data by setting data blocks as valid, erasable, or invalid based on caching and journaling status, ensuring consistent data across the buffer cache, journal area, and storage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If a buffer cache is implemented with nonvolatile medium, then data can be semi-permanently stored, but the buffer cache cannot provide instant access to data like volatile RAM
Solution Approach 1:
The storage system is segmented into multiple nonvolatile memory devices with different characteristics: a first nonvolatile memory device for buffer cache operations and a second nonvolatile memory device for mass storage. This segmentation allows each device to be optimized for its specific function, with the buffer cache device providing faster access and the mass storage device providing durable retention.
Solution Approach 2:
The patent introduces an intermediary mechanism where the buffer cache nonvolatile memory device acts as a mediator between the mass storage device and the host system. Data is first written to the buffer cache device for quick access, then asynchronously transferred to the mass storage device for permanent retention, resolving the contradiction between speed and retention.
2Reliability
If journaling technique is used to manage metadata changes, then file system reliability improves, but network access costs and performance reductions increase in cloud storage systems
Solution Approach 1:
The patent extracts the journaling function from the traditional file system and implements it at the storage device level using nonvolatile memory. The journal is stored in the first nonvolatile memory device, allowing metadata changes to be recorded locally without requiring continuous network communication, thus maintaining reliability while reducing network access costs.
Solution Approach 2:
The patent creates a copy of the journaling mechanism within the nonvolatile buffer cache, allowing metadata changes to be replicated locally before being synchronized with the mass storage. This copying approach ensures reliability through local journaling while minimizing network traffic for metadata operations.
3Ease of operation
If flash memory performs write operations for garbage collection, then data can be managed, but performance and lifespan are reduced due to overhead
Solution Approach 1:
The patent segments the storage system into a buffer cache portion and a mass storage portion, allowing garbage collection operations to be performed independently on each segment. The buffer cache can be cleaned of temporary data while the mass storage maintains its data integrity, reducing the overhead impact on overall system performance.
Solution Approach 2:
The patent performs preliminary data management operations in the nonvolatile buffer cache before they are committed to the mass storage. By pre-processing and cleaning data in the buffer cache, the system reduces the burden on the mass storage device during garbage collection, thereby maintaining higher performance and lifespan.
Data Source
AI summary
An integrated nonvolatile memory control subsystem and method are disclosed. The integrated nonvolatile memory control subsystem includes a nonvolatile buffer cache, a nonvolatile journal area, nonvolatile storage, and an integrated memory control unit. The integrated memory control unit performs a read operation, a write operation, a commit operation and a checkpoint operation on the cache blocks of the nonvolatile buffer cache and the journal blocks of the nonvolatile journal area. The integrated memory control unit sets each of data blocks of the nonvolatile storage as one among valid state, erasable state and invalid state, depending on being cached or not, being journaled or not, and being a clean cache or not, so as to maintain an authentic original up-to-date consistent data within any one of the nonvolatile buffer cache, the nonvolatile journal area and the nonvolatile storage.