Can anyone suggest good apps or methods to test NAND flash speeds in the iPad Air 2 (or iPhone 6 Plus)? Using the Passmark PerformanceTest app, I've tested all iPad Air 2 configurations (ignoring color) except 128GB Wifi. I didn't see major differences between Wifi and Cellular for 16GB or 64GB, so I only list cellular results below, and skipped 128GB Wifi for now. Is there any reason to expect differences between Wifi and Cellular? I've seen speculation the Wifi might be more likely to use MLC (because more space is available), but no such evidence. Average results, 10 trials per device: Size: Write, Read (MB/s) 16GB: 31, 725 64GB: 163, 939 128GB: 181, 947 Are the much higher write speeds for 64GB and 128GB because they use TLC rather than MLC? (I haven't checked the type of NAND in the models.) However, isn't TLC supposed to be much slower than MLC? I recall seeing benchmarks showing TLC was much faster writing zeros (not very useful), but much slower writing random data (much more relevant). Perhaps the benchmark writes zeros? Does anyone know how it works (e.g., type/size of data, all sequential or some random access)? The read speeds are also substantially higher for the 64 and 128 models, but is that another benchmark artifact? I also noticed MUCH higher variability across the 10 trials for the 16GB (vs. the 64GB and 128GB), especially for reading. Should MLC vs. TLC differ in consistency of speed, or is there another explanation? 128GB showed modestly higher write speeds than 64GB, but they presumably both use TLC. Should speeds normally differ in this way based on size (even if both MLC or both TLC), or is that difference likely for other reasons (e.g., variation among individual units or vendors)? It would be nice to see other people post benchmark results (using the app above or a better benchmark), and identify their model, and type of flash (MLC/TLC) if known.