Copy Redundancy in Content Addressable Memory for Key-Value Storage
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Solution Overview
Problem
Conventional content addressable memory (CAM) systems in key-value data storage face limitations due to limited memory capacity and high error susceptibility, leading to 'false negatives' and 'false positives' during data retrieval, as they rely on a single copy of stored keys, which can result in data going unidentified or incorrectly matched.
Innovation Solution
Implementing copy redundancy in CAM by maintaining multiple redundant copies of stored keys, allowing for comparison with input search words and using timestamps to verify data integrity, ensuring data retrieval even if one copy is corrupted, and reducing reliance on volatile memory.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a single copy of stored keys is used in CAM, then memory capacity is optimized, but reliability deteriorates due to error susceptibility and false positives/negatives
Solution Approach 1:
The patent implements copy redundancy by maintaining multiple redundant copies of stored keys in the CAM block. Each key is stored in multiple locations within the CAM, allowing the system to tolerate errors in individual copies while maintaining reliable data retrieval. This directly addresses the contradiction by sacrificing some memory capacity to multiple copies in exchange for significantly improved reliability and reduced false positives/negatives.
2Reliability
If multiple redundant copies of keys are maintained in CAM, then reliability improves, but memory capacity is reduced
Solution Approach 1:
The patent organizes multiple redundant copies of keys across different dimensions within the CAM structure, utilizing various memory locations and associations. This dimensional organization allows efficient use of CAM capacity while maintaining redundancy, as the system can access multiple copies through different address paths and association mechanisms without requiring linear increases in total capacity.
3Device complexity
If conventional CAM systems are used, then device complexity is low, but error correction capability is insufficient
Solution Approach 1:
The patent implements feedback mechanisms through timestamp verification and majority voting logic. When multiple key copies are retrieved, the system uses timestamps to verify data freshness and majority voting to determine the correct key value. This feedback loop enables automatic error correction without requiring complex external error correction codes, maintaining relatively simple device architecture while significantly improving error correction capability.
Data Source
AI summary
A memory system includes a memory device comprising a value data block a content addressable memory (CAM) block storing a plurality of stored search keys. The memory system further includes a processing device that receives an input search key, identifies, from the plurality of stored search keys in a CAM block of a memory device, multiple redundant copies of a stored search key that match the input search key, and determines a plurality of locations in a value data block, the plurality of locations corresponding to the multiple redundant copies, wherein one of the plurality of locations comprises a first timestamp and data representing a value associated with the input search key, and wherein a remainder of the plurality of locations comprises one or more additional timestamps. The processing device further determines whether the first timestamp matches the one or more additional timestamps, and responsive to the first timestamp matching the one or more additional timestamps, retries from the one of the plurality of locations, the data representing the value associated with the input search key.