Data Prefetching via Sequential Stream Recognition

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Solution Overview

Problem

Existing data prefetching techniques in data storage systems struggle to recognize sequential I/O streams due to complex data storage configurations with multiple layers of logical device mappings, leading to inefficiencies and reduced prefetching effectiveness.

Innovation Solution

A method where a front-end component in the data storage system performs sequential stream recognition processing to determine if a read operation results in a cache miss, and if so, instructs a back-end component to prefetch data, updating cache slot headers and prefetch indicators to optimize data retrieval and caching.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If data prefetching techniques are implemented in data storage systems, then data retrieval efficiency is improved, but the complexity of recognizing sequential I/O streams increases due to multiple layers of logical device mappings

Engineering Contradiction:
Improvedata retrieval efficiencyVSAvoidsequential stream recognition complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The patent segments the sequential stream recognition process into distinct components: a determination component that identifies whether I/O requests form a sequential stream, and a data prefetching component that retrieves data based on this determination. This segmentation allows the system to handle complex logical device mappings by breaking down the recognition process into manageable steps, improving data retrieval efficiency without overwhelming system complexity.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent implements preliminary action by determining whether I/O requests constitute a sequential stream before actually performing data prefetching operations. This preliminary determination allows the system to prepare and pre-fetch data in advance of actual requests when sequential patterns are detected, thereby improving data retrieval efficiency while managing complexity through staged processing.

Inventive Principle:
Principle #10Preliminary action

2Reliability

If sequential stream recognition is performed to enable data prefetching, then cache hit ratio is improved, but processing overhead increases

Engineering Contradiction:
Improvecache hit ratioVSAvoidprocessing overhead
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The patent applies partial action by implementing sequential stream recognition and data prefetching selectively rather than universally. The determination component evaluates I/O requests to identify sequential patterns, and prefetching is performed only when such patterns are detected. This selective approach improves cache hit ratio by targeting prefetching at relevant workloads while minimizing processing overhead by avoiding unnecessary analysis of non-sequential requests.

Inventive Principle:
Principle #16Partial or excessive action

3Productivity

If data prefetching is implemented without accurate sequential stream recognition, then resource utilization decreases, but data retrieval performance suffers

Engineering Contradiction:
Improvedata retrieval performanceVSAvoidresource utilization
Core Design Contradiction:
ProductivityVSLoss of energy

Solution Approach 1:

The patent implements feedback mechanisms where the determination component continuously monitors I/O request patterns to identify sequential streams, and this information feeds into the data prefetching component. The system uses this feedback to dynamically adjust prefetching operations, ensuring accurate sequential stream recognition that improves data retrieval performance while optimizing resource utilization by avoiding unnecessary prefetching operations.

Inventive Principle:
Principle #23Feedback

Data Source

PatentUS9830266B1Techniques for data prefetching
Publication Date: 2017.11.28 EMC IP HLDG CO LLC
  • US9830266B1 patent drawing
  • US9830266B1 patent drawing
  • US9830266B1 patent drawing

AI summary

Described are techniques for processing a data operation in a data storage system. A front-end component of the data storage system receives the data operation. In response to receiving the data operation, the front-end component performs first processing. The first processing includes determining whether the data operation is a read operation requesting to read a data portion which results in a cache miss; and if said determining determines that the data operation is a read operation resulting in a cache miss, performing read miss processing. Read miss processing includes sequential stream recognition processing performed by the front-end component to determine whether the data portion is included in a sequential stream.