> The idea that you'll get a faster transfer if you (say) exactly match the erase block size of your SD card doesn't seem to hold much water anymore. No but if

> The idea that you'll get a faster transfer if you (say) exactly match the erase block size of your SD card doesn't seem to hold much water anymore. No but if you use a much lower block size with cheap flash it does get horribly slow. Makes sense because cheap eMMC does not have cache RAM to combine write commands and no NCQ (native command queueing) either. So it has to execute each write as it gets it. I bet you can kill flash pretty quickly this way with a block size of 1. The write amplification will be huge. The problem with the cat method is that you don't really know what it's doing under the hood in terms of write sizes. Probably it will pick something smart but it depends on the OS there and possibly the shell.