FLASH FILE SYSTEM 101
Flash file system design is the foundation of an embedded system; it serves as the glue connecting flash memory hardware with the operating system, allowing the application layer to communicate with the flash. An important component of the flash file system is the flash memory manager, also known as the flash media manager. This piece of the flash file system manages some of the inherent complexities of flash memory and presents the flash to the system as a basic block device, similar to a hard disk drive. The operating system will sometimes include a rudimentary flash file system to enable basic flash file functionality.
A prime example of a flash file system included in the operating system, the WinMobile flash file system is comprised of two parts, TFAT and Microsoft’s FMD flash memory manager. The WinMobile flash file system provides a basic level of flash file management, but when a high-performance/high-reliability solution is required, a professional flash file solution offered by Datalight is recommended. The charts below compare performance between TFAT and the Datalight flash file system solution:
Similarly for Linux, JFFS2 and YAFFS2 provide basic flash file and flash memory manager functionality, and are the two primary Linux flash file system options available in open source. Either JFFS2 or YAFFS2 will provide basic Linux flash file system functionality, but performance is often an issue—particularly in terms of mount times. Both JFFS2 and YAFFS2 are journaling flash file systems which require a long process of checking the disk before the flash disk is able to be used. Below are charts comparing mount times for JFFS2 and YAFFS2 with the Datlight flash file system solution:
As you can see, the “free” flash file system available or included with the operating system may not be the best choice. A professional flash file system or flash memory manager such the Datalight solution will dramatically improve system mount performance. In addition, using Datalight in place of the (JFFS2 or YAFFS2) Linux flash file system or the (TFAT and FMD) WinMobile flash file system will provide data integrity, flexibility in flash part selection, and faster integration. To learn more about the Datalight solution, visit www.datalight.com