On Fri, Mar 20, 2015 at 07:14:19AM +1100, James Cameron wrote:
> This is also a technique to increase longevity in an application,
> because the writes are spread over a larger space, and the lifetime
> is extended.

That reminds me.

How, and are you, powering down the card after an operation?

We found in our XO-1.5 model that the FTL would remain active for some
time after a command.  The FTL is probably preparing erase blocks for
the next write, or moved recently read data to erased blocks.  It
probably has power fail detection.

If we pulled the supply from it too soon, lifetime was affected.  Some
cards would permanently stop responding.  Became a yield issue.

If we pulled the supply too slowly, lifetime was affected.

Fixes were to add a few second delay on power down, and add a
discharge circuit ...

http://wiki.laptop.org/images/a/ad/XO_4_Schematics.pdf (page 34, PQ18,
PQ41, PQ61.

.... and I'm sure I've mentioned my enjoyment of that issue here
before.  ;-)

--=20
James Cameron
http://quozl.linux.org.au/
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