Extending fault tolerance of flash memory

With the onslaught of billions of disparate ‘things’ in the burgeoning Internet of Things, a plethora of data is being generated. The management and storage of such data requires file management systems capable of managing many file types, sizes and formats while ensuring dependable retrieval and storage. FileX does this with sensitivity to different levels of criticality and destinations. Moreover, its implementation of exFAT ensures that overhead, memory and power requirements are kept to a minimum.

“The growth and diversity of data generated introduces many challenges for embedded developers,” said William E. Lamie, CEO of Express Logic. “The FileX file system, coupled with fault tolerance and LevelX flash wear levelling, delivers all the essential tools developers need to easily build reliable and durable flash file systems.”

Improved file and device support and dependability

Always-on devices often require the flow of large amounts of data. File management must be efficient. With its support for exFAT, FileX now manages individual data files larger than 4GB - an important step forward for applications such as HD videos common in medical, business and consumer technology that need to stream large files.

In addition, FileX improves dependability through journaling for fault recovery. By tracking uncommitted file system changes and recording the intentions or changes within the journal data structure, FileX fully supports fault tolerant systems. FileX improves system reliability and prevents data corruption by enabling the recovery of files in the case of a system crash or power failure. Such data management is critical for always-on, mission critical devices.

LevelX helps maximise flash memory durability

LevelX complements FileX for always-on devices, such as wearable heart monitors, in which data is stored locally until it can be uploaded via a network. Such devices typically use NAND and NOR flash, which can be erased and rewritten only a finite number of times. Consequently, such devices must maximise the longevity of usable flash memory. Wear levelling maximises the life of the flash by distributing the storage of memory evenly over the entire flash.

Express Logic LevelX delivers NAND and NOR flash wear levelling through an algorithm that reuses blocks of flash memory on lowest erase count. The algorithm also tracks the number of obsolete mappings to eliminate overheads when moving and mapping new entries. For applications involving multiple instances of NAND and/or NOR flash, developers can use separate instances.

LevelX achieves fault tolerance by performing a multi-step process that is interruptible at any point. LevelX automatically recovers to a coherent state during the next power-up operation. Written in ANSI C, LevelX is easy to install and can be configured at compile time.