Wookey - Aleph One Ltd.

YAFFS - A filesystem designed for NAND flash

YAFFS (Yet another Flash Filesystem) arose from a need for a simple, reliable, lightweight, journalling filesystem for the then-new NAND flash in SmartMedia. Initially, modifying JFFS2 seemed like the obvious way to go, but some research showed that in many ways it made more sense to design something slightly different, catering specifically to the differences between NAND-flash and NOR-flash.

YAFFS was the result, and it's proved to be very good, being used in real commercial products under both Linux and WinCE and on systems from a few MB up to 1GB of flash. The design tries hard to be portable and dual-licensing also allows it's use with non-free OSs such as pSOS and WinCE4.

This talk will cover the NAND/NOR comparison and the corresponding design decisions in YAFFS, give an overview of how it all works under both Linux and in deeply-embedded systems, explain how it differs from other plausible filesystems, and cover the licencing choices we've had to make.

Paper

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