Filesystems for managed flash
As the trend toward managed flash technologies continues, particularly eMMC, we need to consider how to use them effectively. While they appear to have the same characteristics as hard disk drives, the underlying NAND flash chips have the limitations of large erase blocks with limited erase cycles and bad block handling. We also need robustness in the event of power loss.
It is possible to use any of the normal disk filesystems, but we should try to choose one that reduces disk writes and has a fast restart after an unscheduled shutdown.
Flashbench
To make optimum use of the underlying flash memory, you need to know the erase block size and page size. Manufacturers do not publish these numbers as a rule, but it is possible to deduce them by observing the behavior of the chip or card.
Flashbench is one such tool. It was initially written by Arnd Bergman as described in the LWN article available at https://lwn.net/Articles/428584. You can...
