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Method and System for Performing Segregation of Data Being Moved during Data Retention of Flash Blocks to Reduce Write Amplification

IP.com Disclosure Number: IPCOM000245020D
Publication Date: 2016-Feb-06
Document File: 4 page(s) / 48K

Publishing Venue

The IP.com Prior Art Database

Abstract

A method and system is disclosed for performing segregation of data being moved during data retention of flash blocks to reduce write amplification.

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This is the abbreviated version, containing approximately 51% of the total text.

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Method and System for Performing Segregation of Data Being Moved during Data Retention of Flash Blocks to Reduce Write Amplification
Disclosed is a method and system for performing segregation of data being moved during data retention of flash blocks to reduce write amplification. The method and system utilizes a Flash-based Solid state disks (SSD) controller that writes the data out-of-place in a log-structured manner, maintains a logical-to-physical mapping, and includes a garbage collector to reclaim blocks of consecutive physical space. The method and system augments data retention mitigation process with a component that performs segregation of blocks during data retention moves based on static time and data. The process guarantees that ice-cold data found at the time of data retention moves are merged into Logical Erase Blocks (LEBs) to contain only data corresponding to the data retention moves. Essentially LEBs with data retention moves are defragmented into LEBs of ice-cold data that are unlikely to be invalidated.

During the data retention mitigation process, data that is sitting idle for long periods of time is moved or relocated at constant time interval. The relocation of the data is carried out in order to re-use blocks containing that data and avoid high error counts due to data retention effects. Due to re-use of blocks containing that data, the balance of data across the blocks of a system is controlled. The frequency at which any block containing valid data is moved for data retention process depends on characteristics of a flash technology, which is tightly related to data retention effects. Typically, the method and system checks whether all the blocks hold valid data or not and moves the valid data out of the blocks before exceeding a predefined data retention time limit of the blocks. The predefined data retention time limit may include, but need not be limited to, a few weeks or few days and like.

Data that is not invalidated within the data retention window is essentially staying idle for a significantly long period of time. This is a good indication of static or...