LogFS. LogFS is a Linux log-structured and scalable flash file system, intended for use on large devices of flash memory. It is written by Jörn Engel and in part sponsored by the CE Linux Forum. LogFS is included in the mainline Linux kernel and was introduced in version 2.6.34, released on May 16, 2010. In contrast to JFFS2, YAFFS, and UBIFS, LogFS also provides a (very) basic, slow support for use with block devices like solid-state drives (SSDs), USB flash drives, and memory cards.[1] History[edit] As of November 2008[update], LogFS was mature enough to pass its entire test suite, and was subsequently included in the mainline Linux kernel, marked as 'experimental', in version 2.6.34 released on May 16, 2010.
Operation[edit] A flash-memory block is the unit for erasures and is usually larger than the file-system block. Logfs in Action[edit] The latest logfs source is available from logfs git tree. See also[edit] External links[edit] References[edit] Jump up ^ LogFS news (see 9.7.07) YAFFS. Yaffs (Yet Another Flash File System) was designed and written by Charles Manning, of Whitecliffs, New Zealand, for the company Aleph One. Yaffs1 was the first version of this file system and was designed for the then-current NAND chips with 512 byte page size (+ 16 byte spare (OOB;Out-Of-Band) area). Work started in 2002, and it was first released later that year. The initial work was sponsored by Toby Churchill Ltd, and Brightstar Engineering. These older chips also generally allow 2 or 3 write cycles per page,[clarification needed] which YAFFS takes advantage of - i.e. dirty pages are marked by writing to a specific spare area byte.
Newer NAND flash chips have larger pages, first 2K pages (+ 64 bytes OOB), later 4K, with stricter write requirements. Each page within an erase block (128 kilobytes) must be written to in sequential order, and each page must be written only once. YAFFS2 was designed to accommodate these newer chips. YAFFS1[edit] YAFFS2[edit] See also[edit] References[edit] Systems, Inc. NAND Flash Software. Home. JFFS2: The Journalling Flash File System, version 2.
What is JFFS2? JFFS2 is a log-structured file system designed for use on flash devices in embedded systems. Rather than using a kind of translation layer on flash devices to emulate a normal hard drive, as is the case with older flash solutions, it places the filesystem directly on the flash chips. JFFS2 was developed by Red Hat, based on the work started in the original JFFS by Axis Communications, AB. How does it work? A paper which was presented at the Ottawa Linux Symposium 2001 describing the development and operation of JFFS2 is available here, both in its original PDF form and also converted to HTML. The slides which accompanied the talk are also available in PDF form, here. What operating systems does JFFS2 work under? JFFS2 works in Linux (v2.4 and later) and eCos Where can I get it? JFFS2 has been included in the official Linux kernel since the 2.4.10 release.
The source for the mkfs.jffs2 utility is also in the CVS tree, in the util/ directory. Where can I get more information? JFFS2 source code documentation.