LINUX EMBEDDED SYSTEM 101
Linux embedded system software consists of the Linux-based operating system (the kernel) itself, application software, embedded file system and various plug-ins and drivers used to connect with other devices and/or peripherals. A Linux embedded system, like all embedded system software is designed for small mobile devices or other resource-constrained environments such as industrial automation, set-top boxes, and medical machinery.
Due to space constraints and harsh environments the memory storage in a Linux embedded system is typically provided by flash memory, the complexities of which make the embedded file system an extremely important piece of the system.
Linux embedded system designers have several choices when it comes to which embedded file system to use. These include JFFS2, YAFFS2, EXT3 (which is a file system only), and a commercial Linux embedded file system produced by Datalight.
| Feature | JFFS2 | YAFFS | Reliance & FlashFX Pro |
| Startup performance (mount times) | 2.3 sec | 1.0 sec | 0.5 sec |
| General performance (I/O throughput) | 0.6 MB/s | 1 MB/s | 1.2-14.0 MB/s |
| Support for latest Flash technologies | NAND and NOR | NAND only | NAND, NOR, fusion flash and NAND Controllers (over 200+ parts supported) |
| 100% reliable in the event of power loss | No | No |  |
| Wear Leveling | Static + Dynamic | Dynamic only | Static + Dynamic |
As shown above, JFFS2 lacks the performance required by today’s Linux embedded system designers. With the mobile device industry shifting to the denser and cheaper storage of NAND, Linux embedded system software has had to catch up. While YAFFS2 has overcome the NAND performance challenges of JFFS2, Linux embedded system developers are still seeking faster solutions. Addtionally, YAFFS2 has been proven to have reliability gaps, such as dynamic-only wear leveling and lack of power-loss integrity. Many device manufacturers using Linux are finding it necessary to use a commercial embedded file system, such as the one provided by Datalight. The charts below show the significant performance benefits offered by the Datalight flash memory manager and file system.
As shown in the examples above, the “free” embedded file system provided in open source may not be the best solution for your device. For more information about the embedded file system for Linux available from Datalight, visit www.datalight.com/wickedfast
Also available:
Datalight VxWorks embedded file system
Datalight WinMobile embedded file system