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A Method and System for Prolonging Life of a Flash Memory by Swapping Rapidly Aging Blocks with Reserve Blocks

IP.com Disclosure Number: IPCOM000235554D
Publication Date: 2014-Mar-08
Document File: 2 page(s) / 66K

Publishing Venue

The IP.com Prior Art Database

Abstract

A method and system is disclosed for prolonging the life of a flash memory by swapping rapidly aging erase blocks in a Multi Level Cell (MLC) mode with reserve erase blocks kept in a Single Level Cell (SLC) mode.

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A Method and System for Prolonging Life of a Flash Memory by Swapping Rapidly Aging Blocks with Reserve Blocks

A memory cell can store 1 bit when in a Single Level Cell (SLC) mode, as opposed to, storing 2 bits when in a Multi Level Cell (MLC) mode. Current methods have demonstrated that a life of a memory cell can be prolonged by switching the memory cell from the MLC mode to the SLC mode. However, switching each memory cell of a flash memory is expensive. Therefore, there is a need to prolong the life of the flash memory without switching each memory cell in the flash memory to the SLC mode.

Disclosed is a method and system for prolonging the life of a flash memory by swapping rapidly aging erase blocks in a MLC mode with reserve erase blocks kept in a SLC mode. Swapping involves setting the rapidly aging erase blocks to the SLC mode and, setting the reserve erase blocks to the MLC mode.

In one embodiment, the reserve erase blocks kept in the SLC mode can be parity erase blocks used in storing parity data in a Redundant Array of Independent Disks (RAID) device.

The method and system includes reserving a percentage of erase blocks in the flash memory for maintaining in the SLC mode. The percentage reserved corresponds to a percentage of the parity erase blocks. For example, if the RAID array uses one cell for storing parity data for fourteen cells, then the percentage of erase blocks reserved is 6.667%. The method and system subsequently uses a RAID controller for setting parity data for multiple erase blocks corresponding to a range of logical block ad...