> Sounds like a buggy FTL (flash translation layer) that doesn't
> properly handle corruption of flash cells.  You're meant to be
> given an error response.

Well, I'll have to wait and see if the card fails again in the next
day or so using the same rate of reads. If it does then perhaps I
can look for something like a Data Error Token. Regrettably I
didn't save the analyser trace which I believed showed the fail
so I can't say whether there was a DET

Due to the nature of the data, a corrupt bit or two isn't that
important. Imagine one pixel of a jpeg being not quite right. I
expected to be able read a block completely, regardless of
whether its contents are correct or not, but it looks like the
card might not actually be able to read the cell(s), whatever
value is there and sends a one-byte DET instead of a block

At this stage it's hard to say what the failure mechanism is. After
a re-format and re-load the card seems to be behaving, so it
"can't" be something physically broken. If it fails again soon then
I'll have something to work on. If it doesn't then I'll be haunted
by what might happen when it's out the door

Joe


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