On Monday 12 April 2010 17:06:19 Charles Manning wrote: > You'd probably do far better to ask questions like this on the linux-mtd > list or similar. > > I'm the author of the yaffs file system, so I can answer some of your > questions though. > > Pretty much all flash file systems or flash management layers such as UBI > perform at least some degree of wear levelling. This means that there is > some sort of logical to physical, or other, policy so that the writes don't > happen in the same place. That means those writes to a certain file will > end up being spread across many different blocks, thus meaning that writes > to one particular file won't wear out one part of flash. > > And yes, the endurance depends on the type of flash. Some are of the order > of 10^6, some are only 10^3. > > Worst I've seen is 10^2, but that was for a "bootloader" section and not > designated for file usage.
Apparently it's not just the chip, but also depends on how the flash is wired up. (At a co-worker's previous company they had horrible flash reliability problems until an engineer went in and redid the wiring on the board. Grounded it properly or something, I dunno. Got it back up to 10^6 without changing what chip the design was using.) My takeaway from it was "flash is hard ot get right electrically, and you may not notice until later". Rob -- Latency is more important than throughput. It's that simple. - Linus Torvalds _______________________________________________ busybox mailing list [email protected] http://lists.busybox.net/mailman/listinfo/busybox
