Power Down

[Bob Canup]

Watch dogs are generally there to catch the problem of a run-away
machine - this ought to be a very rare occurrence.

According to Vipin's statistics about 1 in 250 random power failures
during writes to a DOC2000 results in a bad sector on the device. Since
you are required to run the chip in RW mode the only way I see to avoid
the problem is a UPS on the front end - with signaling to indicate power
failure so that an ordered shutdown could occur.

As far as the problem of a bad sector which he discussed I have not seen
any solutions other than the erase and start over one he originally came
up with - which for the reasons he discussed - is unacceptable.

The first step toward solving a problem is understanding exactly what
the problem is. My theory is that if you interrupt a sector write while
it is in progress the data and the error checking code don't match -
thus you get a bad sector. Any other theories?





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