http://www.datarescue.com/laboratory...pare/index.htm


I belong to the local Disney club. We meet one or two Saturdays a
month. I go to Disney 3 or 4 times per year and each time I take the
digital camera. Because of the water rides, sweat, crowds, and
handling, I've gone through several digital cameras. I've also gone
through several flash cards for each because they went dead. There
isn't anyone in the Disney club that doesn't take spare cards simply
because they all know they will probably lose one on a trip (lose as in
it dies, not that they misplace the card or it gets stolen). Good for
you that your cards have survived your handling and use of them. That
viewpoint doesn't seem prevalent in my realm of friends using them.

The fault tolerant (or wear leveling) algorithms are to mask failures
until they exceed the ability to be masked. As masking increases,
capacity decreases. Also, flash memory slows over time (but is still
probably more than fast enough for its *intended* use). The controller
in the flash card tries to level the wear by spreading out the remapping
so, as you say, the device dies suddenly rather than becomes crippled
and perhaps unusable because just one area is overly worn. See
http://www.storagesearch.com/siliconsys-art1.html.

As for using the flash card as, say, temp file space, a million or two
or three programming cycles sounds real high until you realize how often
files are rewritten in this temp space. I've seen anti-virus products
write to a file in temp space at 2900 writes accesses per minute (I was
checking at the time why EzAntivirus and Prevx seem to get into a
thrashing mode with each other on the same files). After 6 hours,
there's a million writes. Hopefully the silicon-based controller on the
flash card works its remapping wonders so wear leveling gradually moves
all those writes to less worn blocks but then most folks want to use
their computer more than 6 hours, 6 days, 6 weeks, and maybe even up to
6 years. Obviously this situation isn't normal. The user could use
Filemon from SysInternals to see how often they are making writes into
the temp space in which they want to employ a flash card. Don't know
which hard drives you or the OP buy but mine usually last more than 5
years. I don't think a flash card will make it past several months but
that's just a guess and based on the death rate that I've experienced.
Maybe you've been luckier than our Disney group of shutterbugs.

That's not to say silcon disks aren't far better than mechanical hard
drives. SSDs are far better - at a hefty price - than are hard drives.
See http://www.storagesearch.com/bitmicro-art3.html. But these are
SSDs, not flash cards.