Programmer Humor

I wasn't aware that that existed. Guessing it didn't also raid each of the inserted drives, so it would have at best given 2x microsd performance, though at worst it would be as slow as your slowest one. Actually mismatches of performance from microsd to microsd could have even cause further performance issues if the raid controller assumes equal performance so that the read responses can be interleaved with some small amount of buffer space. It could mean one getting too far ahead of the other would end up requiring transactions to be re-issued. Even if they were all identical, I wouldn't expect them to degrade at the same rate.

Though now I am curious about how well a large number of microsd cards would perform if set up in an array that striped/mirrored across all of them rather than batches of them, with sufficient buffer space to absorb perf differences between the cards (meaning it would still be held back by the slowest cards but not to the point of thrashing, if that was an added factor in your setup).