And was salivating at the prosepct of paying £18 for 16GB of PRO DUO storage instead of £55. That’s right, you can pop in 2 Micro SD cards up to 16GB and use them both as one drive in PRO DUO devices. It seems too good to be true, but it works and apparently there are no drawbacks. The only problem was that these £8 8GB Micro SD cards were only Class 2, meaning I may have to shell out more making it less of a bargain, there was lots of information available on the “minimum” write speeds of SD cards and the “maximum” write speeds of PRO DUO cards but I couldn’t find any concrete data on how fast cards should actually be.

So as usual I went crazy and I decided to benchmark a few cards to see if I would be losing out by using 2 Micro SD cards instead of a normal PRO DUO and to see if I was going to be sitting around checking my watch while this “Class 2″ SD card loaded stuff. Read on for graphs etc.

So first off I found myself a disk benchmarking program, this was quite easy, ATTO Disk Benchmark seemed to fit the bill, so I fired it up and did some quick benchmarks on the memory cards I had to hand which were:

• Sandisk 4GB Micro SD (Class 2)
• Sandisk 2GB Micro SD (Unknown Class)
• Sandisk 4GB Extreme III PRO-HG DUO (Pro HG features not used in this test)
• Sandisk 2GB PRO DUO MK1

Not the best spread, but I had what I needed, 2 memory cards of each type I wanted to check, good enough for me. If there were any massive differences then I would see them from this pool of test cards. I tested them with file sizes up to 8MB with separate read/write as combining read write was not relevant in this case.

Sandisk 2GB PRO DUO MK1	Sandisk 4GB Micro SD (Class 2)
Sandisk 4GB Extreme III PRO-HG DUO	Sandisk 2GB Micro SD (Unknown Class)

As you can see from the above charts it seems like the Micro SD read speed even though it is a Class 2 card is still much higher than the read speeds of the PRO DUOs. It’s nice to see that the Extreme III get such a nice write speed and actually surpassed it’s read speed, I assume this is because the Extreme III is HG card and had I been using a HG card reader the read speed would have been something like 20-30MB/s, but these devices aren’t exactly mainstream.

I think it’s safe to say that I shouldn’t have any problems with the speed rating of the cards when putting them in the PRO DUO adapter. Once I have it and 2 8GB cards delivered I’ll give that a test too and see how it does. If you want to take a look at the data yourself here’s the raw data. In the meantime here’s the read/write graphs for all the cards shown: