On 09/27/2010 11:50 AM, Mark Morgan Lloyd wrote:
We have equipment scattered around Europe, and the reliability of the
power sources on industrial sites is far worse than most people
appreciate. A common scenario is where our kit is wired to a supply
that intermittently runs a pump or similar, i.e. sometimes it sees
230V but most of the time it doesn't.
Non Card based directly managed flash chips with file systems like JFFS2
and UBIFS that handle the wear leveling in the file system code itself
can be made secure, as it is clean after unmounting and the system can
know if the unmount has been completed. Moreover the journaling can take
wear leveling into account and (maybe) it even can be rolled back clean
to the last transaction completely stored on the flash ship.
But this does not help with flash cards as they might destroy seemingly
stored data when storing of other data is aborted.
I was even told about cards that could not even be formatted after an
aborted write (obviously the writing to a a page management page has
been aborted.) It was completely dead but _could_ be reconfigured by the
manufacturer.
-Michael
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