A warning from RiData

Started Jul 20, 2008 | Discussions thread
bob elkind Veteran Member • Posts: 5,815
PLEASE read this

I'm a design engineer, I work with flash memory a fair bit, and there are some important messages to convey and some erroneous conclusions to be corrected. PLEASE READ THIS...

Tom Kuwahara wrote:

Just bought the 8GB 233x for $39.95 at Frys Electronics. Then I
checked their website for the 233x Lighting Series. I found this
statement directly on the Lighting Series site:

Consumer Notice:

For Digital SLR camera users (such as Nikon, Canon SLR DSCs etc.) we
recommend using the Ridata Single Layer cell (SLC) based CF cards for
these high performance cameras. We suggest using the Ridata 150x or
266x CF SLC cards for maximum performance. It has come to our
attention that while using the “continuous shot” mode and Multi Layer
Cell (MLC) cards such as the Ridata 233X CF Card, problems may occur
due to the slower data writing limitations of the Multi Layer Cell
(MLC) specifications and users may experience an image corrupt

Erroneous conclusions:

1. This problem is NOT endemic to all MLC-based memory cards. For example, Sandisk Extreme III cards are MLC, and they work fine, and they support UDMA transfer modes.

2. This problem is NOT endemic to memory chips from a specific manufacturer (e.g. Micron).

So don't throw away your MLC-based flash memory cards (assuming you can tell the difference between SLC and MLC-based cards).

Don't throw away your Lexar cards because they use Micron memory chips. Sandisk and Lexar have been very steady with their cards' designs and reliablity, and (at least) Nikon has verified their (Sandisk + Lexar) cards to work well with Nikon UDMA data transfer implementations in the D3 and D300 camera bodies.

Gratuitous interpretation of Ridata's statement:

A. There's either a design bug (e.g. incorrectly programmed memory card controller chip) or production screw-up (e.g. bought a slow speed grade of memory chips to put on the card, and we didn't run the right production tests to catch the error) on the Ridata MLC-based memory cards, by Ridata's own admission.

B. Ridata doesn't have adequate production testing on their production line. Regardless of which Ridata card you own or might own, would you want to buy or use cards from a company that sloppy ? Personally, I would not. There are too many competitive alternatives available.

C. There are several plausible candidates for the fundamental flaw:

1. We designed the card to use a certain memory chps speed grade, and we used cheaper/slower parts in production. Our production tests don't cover full-speed transfers adequately.

2. We programmed the controller chip on the card (this is the data flow traffic cop on the card) to expect a different (faster) speed grade of memory than we actually put on the production boards. Our production tests don't cover full-speed transfers adequately.

3. The controller chip has a design bug, and it's implementation of UDMA transfer protocol is flawed. As a result, data gets lost. And we didn't adequately test this aspect of the design before we went to production. Our production tests don't cover full-speed transfers adequately, either.

I'm returning my card asap.

I wouldn't trust any recent Ridata cards with data I could not afford to lose. Sloppy production tests are rarely isolated to a single product line within a company. There are too many solid and competitive alternative options available.

Having said all this, there is at least one other MAJOR memory card brand that seems to be having similar problems with their cards running on UDMA-capable camera bodies. It shouldn't be hard to ID that company, and you don't need to worry about Lexar and Sandisk.

A pint needs to be made -- Lexar and Sandisk cards are not immune to failures. BUT... there's an important difference between isolated component failures and systemic design/production failures. Isolated component failures are inevitable in a mass-production product. Production test shortcomings of a key operational mode are a result of outright sloppiness -- they are very much avoidable.

Hope this helps. Thanks to the original poster for this thread, this was valuable information.

-- hide signature --

Bob Elkind
Family,in/outdoor sports, landscape, wildlife
photo galleries at http://eteam.zenfolio.com
my relationship with my camera is strictly photonic

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