I have just looked at the old microSD card on a computer. It looks like it was the /psp partition that has failed. So given this is the partition is the one with the most dynamic content I'm wondering if the flash just wore out.
So my question is, given that things like ntp.drift, volume level, alarm changes etc are written here, I'm surprised that flash wearing out isn't a more common problem (or is it a common problem?).
On a busy Chumby I could imagine maybe a write to this partition more than hourly (the drift file is written hourly even on an idle Chumby). So the same piece of storage is probably tweaked hourly (say the blocks holding the directory information). So flash storage can tolerate what 10,000 write cycles, so assuming a write per hour that would be about 416 days. Not so long.
This is maybe a fairly pessimistic estimate and really depends how data is written (files opened and written over the top of existing content or a new file replacing ) but on ext3 (a non-flash aware FS block reuse could, I'd imagine, be potentially very high). This is especially true if we are thinking about the directory data itself.
Now I don't believe that SD cards (unlike flash hard disks) do any hardware based wear leveling.
So my questions would be, is this an issue often seen?
And even though plain ext3 is nice to have why was the dynamic partition not implemented with a more flash friendly file system (that does wear leveling)?