Benchmark Results: Random Reads And Writes
Random reads of 512 KB blocks yield the very same ranking as sequential reads. Once again, the SanDisk Mobile Ultra microSDHC is the fastest card at 21.8 MB/s.
Reducing the block size for the random read test to 4 KB significantly impacts performance, which tops out at a mere 3.4 MB/s, achieved by the Samsung and Adata Class 6 cards. There is almost no difference between queue depths of one and 32 when it comes to memory cards.
Randomly writing 512 KB blocks is not a strong suit for microSDHC cards. The three cards that perform best are the SanDisk Mobile Ultra microSDHC, the Adata microSDHC Class 6, and the Samsung card.
Benchmarking random 4 KB writes yields a rather pathetic picture, with the throughput of all but two test candidates dropping to zero-point-zero-something MB/s. In other words, that's just a few KB/s. Only the SanDisk microSDHC card and the Silicon Power card stand out with a queue depth of one. Unfortunately, that's still just over 1 MB/s.