Flash Memory Page Selection for Read Speed Optimization

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Solution Overview

Problem

Flash-memory storage devices with multi-level cells (MLCs) increase storage capacity but require longer read times, and existing methods to improve reading speed either sacrifice storage space or are inefficient, as they either leave slower parts unused or do not optimize reading speeds across all data types.

Innovation Solution

The method involves storing fast-reading data in 'fast pages' and filler data in 'slow pages' within the flash-memory storage device, allowing for variable read speeds without wasting storage space, by interleaving data based on reading requirements and using a split storage approach where necessary.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If MLC technology is used to increase storage density, then storage capacity is doubled, but read time increases

Engineering Contradiction:

Improvestorage capacityVSAvoidread time

Core Design Contradiction:

Quantity of substanceVSLoss of time

Solution Approach 1:

The storage device is segmented into multiple channels, with at least one fast channel and one slow channel. Data is selectively assigned to different channels based on read speed requirements, allowing simultaneous access to both fast and slow storage regions without interference

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the storage device are assigned different quality characteristics - fast pages in the fast channel provide rapid access for critical data, while slow pages in the slow channel provide capacity for less time-sensitive data. Each region is optimized for its specific function

Inventive Principle:

Principle #3Local quality

2Speed

If only fast pages are used to improve read speed, then reading speed approaches SLC speeds, but storage space is significantly reduced

Engineering Contradiction:

Improveread speedVSAvoidstorage space

Core Design Contradiction:

SpeedVSQuantity of substance

Solution Approach 1:

The system dynamically selects which channel (fast or slow) to use based on the read speed requirements of the specific data being accessed. This allows the storage capacity to be fully utilized while maintaining high read speeds when needed

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system changes the operational parameter (read speed requirement) to determine data placement and access strategy. Data with high read speed requirements is placed in fast pages, while data with lower requirements can be placed in slow pages, optimizing both speed and capacity

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS7779217B2Systems for optimizing page selection in flash-memory devices

Publication Date: 2010.08.17 SANDISK ISRAEL LTD

AI summary

A storage device is provided. The storage device includes a memory that includes interleaved fast and slow pages and a controller. In response to a command from a host of the storage device the controller stores fast-reading data in the memory. If the fast and slow pages alternate, the controller stores the fast-reading data in the first pages alternately with filler data in the low pages, and if contiguous pluralities of the fast and slow pages alternate, the controller stores the fast reading data in the contiguous pluralities of the fast pages alternately with the filler data in the contiguous pluralities of the slow pages.