Re: [gentoo-embedded] file system question

[Peter Stuge <peter@stuge.se>]

David Relson wrote:
> The device has a watchdog (recently activated) and during today's
> session it was triggered and wiped out my file system.
> 
> Anybody have recommendations on which file system to use and the
> appropriate settings?

I would consider ext3. In order to deal with sudden resets (or power
loss) you really want a journalling filesystem. In that case you can
lose data (and need to check for, and handle, that on startup) but at
least the filesystem will be structurally ok.

Which filesystem to use on the flash module depends mostly on the
circumstances of systems in the field, such as how often they are
serviced, service personnel skill level and so on.


> Anybody have suggested readings so I can educate myself?

Hm, not so much. :\ The situation you're in is probably pretty
common, I have customers in the exact same situation, but it is very
different from what JFFS2, YAFFS and friends are made for, which is
that the filesystem actually has direct contact with the flash array.

Any kind of consumer level flash module, including disk-on-modules,
CF, SD, you name it, implements wear-levelling transparently. And
everyone considers their particular wear-levelling to be an important
competitive advantage, so they'll never give out details. The likes
of JFFS2, YAFFS require immediate addressing of NAND flash chips
connected to some bus, but that's never the case unless you're making
your own PCBs.


//Peter