Solid-State Cache Metadata Management via Unified Indexing
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Solution Overview
Problem
Current cache grooming operations on solid-state storage devices are inefficient due to being separate from other memory management operations, leading to suboptimal performance in managing cache metadata and storage metadata.
Innovation Solution
Implementing a solid-state storage device that maintains shared metadata structures, including cache metadata and storage metadata, to efficiently manage caching and grooming operations by using a forward index for logical addresses and a reverse index for physical addresses, allowing for efficient cache eviction and storage operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If cache grooming operations are performed separately from other memory management operations, then cache grooming can be performed independently, but cache management efficiency deteriorates and performance is suboptimal
Solution Approach 1:
The patent combines cache grooming operations with other memory management operations into a unified metadata structure. The forward index and reverse index are integrated with cache metadata, allowing grooming, caching, and memory management to be performed simultaneously through a single management apparatus, eliminating the performance penalty of separate operations.
Solution Approach 2:
The metadata structure serves multiple functions simultaneously: it manages cache entries, performs grooming operations, and handles memory management tasks. The forward index maps logical addresses to physical addresses while also serving as a grooming target, and the reverse index enables both cache lookup and grooming identification, making the system multi-functional and efficient.
2Adaptability or versatility
If separate metadata structures are used for cache management and grooming, then management operations can be performed independently, but storage overhead increases and performance decreases
Solution Approach 1:
The patent merges cache metadata and grooming metadata into a single unified metadata structure. The forward index contains both cache mapping information and grooming identification data, while the reverse index provides both cache lookup capability and grooming target identification. This consolidation eliminates duplicate metadata storage and reduces overall storage overhead.
Solution Approach 2:
Each metadata structure serves dual purposes: the forward index functions as both a cache mapping table and a grooming target identifier, while the reverse index serves as both a cache lookup index and a grooming selection mechanism. This multi-functionality reduces the total quantity of metadata required compared to separate structures.
3Device complexity
If traditional cache structures are used without shared metadata, then implementation is simpler, but data access times increase and cache management becomes less efficient
Solution Approach 1:
The patent pre-organizes metadata into forward and reverse indexes that are optimized for both cache operations and grooming operations. This preliminary structuring allows the system to perform both cache access and grooming identification without additional lookup steps, reducing data access time despite the increased metadata structure complexity.
Solution Approach 2:
The unified metadata structure acts as an intermediary that simultaneously supports both cache management operations and grooming operations. The forward and reverse indexes serve as mediators that translate cache access requests and grooming operations into efficient physical address lookups, reducing overall access time despite the additional structural layer.
Data Source
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AI summary
An apparatus, system, and method are disclosed for an caching data using a solid-state storage device. The solid-state storage device maintains metadata pertaining to cache operations performed on the solid-state storage device, as well as storage operations of the solid-state storage device. The metadata indicates what data in the cache is valid, as well as information about what data in the nonvolatile cache has been stored in backing store. A backup engine works through units in the nonvolatile cache device and backs up the valid data to backing store. During grooming operations, the groomer determines whether the data is valid and whether the data is discardable. Data that is both valid and discardable may be removed during the grooming operation. The groomer may also determine whether the data is cold in determining whether to remove the data from the cache device. The cache device may present to clients a logical space that is the same size as the backing store. The cache device may be transparent to the clients.