[Leica] M9-SDHC Compatibility Issues

[spencer at aotera.org (Spencer Cheng)]

On Aug 9, 2011, at 21:50, Forrest Herr wrote:
>    The reason they are advising against formatting your older cards
> is because Flash memory has a finite number of write cycles.  This
> means that if you perform lots of write operations on your Flash
> memory, eventually it will wear out, and you will experience data
> loss.  The other side effect is that your camera might behave
> strangely because it is trying to read or write to "bad" sectors on
> the memory card, which can cause the camera to lock up.
> 

The number of write cycle w/o wear levelling for modern's flash cards is 
100K+ write cycles ie. you have to take at least 50K pictures * number of 
pictures that fits on the card before wear should become an issue. As very 
few photographers gets to that level of write cycles on any single SD card, 
I am not sure why Leica would offer this advice.

> It sounds like users are experiencing problems with bad memory, or
> heavily used memory cards.  So if you're shooting professionally it
> would be prudent to cycle your older memory cards out of use after a
> year or two.

Possibly but that means the pro would have to fill that card about 50K times 
before it wears out. Assume 400 images per card, that is 20 million images 
has to be taken with that card. That's a lot of images on a single card. I 
would guess the camera is obsolete long before the card wears out.

SD cards do go bad but for photographic purposes, wear doesn't seem to be an 
real problem.

Regards,
Spencer