Summary: how to reduce risk of failure, how to assess ESD consequence.

On Wed, Mar 18, 2015 at 01:21:43PM +1300, IVP wrote:
> I found this reference to read errors
>=20
> http://en.wikipedia.org/wiki/Flash_memory#Read_disturb
>=20
> This card's controller doesn't seem to be doing its job if
> errors are happening and not being corrected at a fraction
> of the expected number of cycles

Some FTLs may use ECC or other forms of redundant data, but as the
FTLs are closely guarded secret code, we don't know.

> With bunniestudios expose in mind, can I trust any card ?

Yes, after testing.

Batching, yield measurement, warranty agreements with manufacturer;
all these things are useful to some extent, but eventually it boils
down to either you test them or they test them.

On Wed, Mar 18, 2015 at 01:33:18PM +1300, IVP wrote:
> > I'd also consider ESD to the card ... not as a solution, but
> > as a source of problems.
>=20
> I think the card is fairly well connected in situ. All data and
> comms lines have the recommended pull-ups, nothing is floating,
> good power supply etc

Consider ESD in handling, between the time the card was fabricated,
and the time you inserted it.

ESD isn't an always an instantaneous failure; it can do damage that
develops over time, such that a part will work fine for months before
failing.

But you're dealing with a single part, which is kinda outside my
experience; what matters are the statistics for the batch, and you can
never tell where a single part sits on the distribution.

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