Flash translation layer

Some subsystems are often called flash file systems, while they are more precisely block drivers performing different translations, and they actually do not have a file system interface. Such subsystems include the following:

TrueFFS

Despite the name, TrueFFS is not a file system at all; it does not provide a file system interface but a disk interface. TrueFFS is correctly termed a flash translation layer. True flash file system or TrueFFS is designed to run on a raw solid-state drive (most modern consumer SSDs are not raw). TrueFFS implements error correction, bad block re-mapping and wear leveling. Externally, TrueFFS presents a normal hard disk interface.

TrueFFS was created by M-Systems[1] on well-known "DiskOnChip 2000" product line, who were acquired by Sandisk in 2006. A derivative of TrueFFS, called TFFS or TFFS-lite, is found in the VxWorks operating system, where it functions as a flash translation layer, not as a fully functional file system. A flash translation layer is used to adapt a fully functional file system to the constraints and restrictions imposed by flash memory devices.

ExtremeFFS

ExtremeFFS is a technology developed by SanDisk (which acquired M-Systems) allowing for improved random write performance in flash memory compared to TrueFFS. Sandisk claimed that the technology improves random access speed in Solid-state drives by a factor of 100.[2][3] In 2008 the company promoted using ExtremeFFS in a multi-level cell implementation of NAND flash memory.[4]

See also

References

  1. ↑ US patent 5404485, "Flash file system, Amir Ban"
  2. ↑ Tony Smith (November 5, 2008). "SanDisk pitches 100x SSD speed boost tech: Slow random writes hidden in fast sequential writes". The Register. Retrieved October 23, 2016.
  3. ↑ "SanDisk Technical Expertise and Metrics". Promotional web site. Sandisk. Archived from the original on November 8, 2008. Retrieved October 23, 2016.
  4. ↑ Chris Mellor (November 28, 2008). "SanDisk flash holds secret flash sauce till after Christmas". The Register. Retrieved October 23, 2016.


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