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Embedded database links up with NAND flash filesystem

Jan 11, 2006 — by LinuxDevices Staff — from the LinuxDevices Archive

ITTIA says it has integrated its recently introduced embedded database with a wear-leveling open source NAND flash filesystem from Aleph One. The Fuel database supports YAFFS (yet another flash filesystem) as an OS driver, or as a direct plugin module, for embedded systems that lack operating systems, ITTIA says.

Wear-leveling flash filesystems such as YAFFS aim to distribute write operations across the entire physical flash memory device, because Flash memory pages typically support only several hundred thousand write operations before becoming unreliable. Flash filesystems may also attempt to identify and route around damaged pages within flash devices. NAND filesystems must also write in page size chunks, or buffer writes until they make up a full pagesize, because NAND flash pages support only 1-3 write operations between erasures, depending on manufacturer specifications. The Linux 2.6 kernel supports both JFFS2 and YAFFS.

ITTIA is a small database consulting company best known for maintaining the db.* embeddable database. The company launched its Fuel database late last year, saying it wrote the product from scratch to meet embedded database needs, after more than a year of design research.

Aleph One specializes in embedded device development. The UK-based company launched YAFFS in September of 2002, calling it the only filesystem on any operating system that was designed specifically to support NAND flash.

Other flash filesystem support for NAND has been available to Linux devices for several years. NAND flash chipmaker Samsung released its proprietary RFS NAND filesystem in 2004, and JFFS2's NAND flash support arrived in March of 2001 and was merged into the stable Linux kernel in 2003. However, JFFS2 was based on JFFS, which was originally written to support NOR flash. (A brief article comparing NAND and NOR flash is available here.)

ITTIA calls the YAFFS filesystem “superior,” and says it worked with Aleph One to verify the interoperability of Fuel and YAFFS. YAFFS can be used as a filesystem driver in the operating system, or linked directly with Fuel to bypass the OS, ITTIA says. YAFFS can also be linked with Fuel to support devices that lack an operating system entirely.

ITTIA says it designed Fuel for performance and a small footprint, and to support persistent storage on devices powered by batteries and other unreliable power sources. More details about Fuel can be found here.

ITTIA and Aleph One plan to jointly market their combined solution, they say.
Aleph One GM Laurie van Someren stated, “We developed YAFFS to provide a high reliability / high performance embedded file system on NAND flash. We believe [YAFFS and Fuel] provide a highly effective embedded data storage solution, and look forward to further cooperation and developments.”

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