Hi, all your dd runs are allowed to make heavy use of RAM buffering. If you are interested in the speed of the storage device, add option oflag=dsync to the dd run.
I use dd options bs=1M status=progress oflag=dsync in order to get realistic pacifier messages when copying ISOs to USB stick. The overall time until a 35 MB/s stick stops blinking is not longer than without those options. Just progress is smooth and dd does not end before the stick is done with blinking. Maybe bs=4K is a bit small for oflag=dsync and unrealistic in comparison to Linux kernel behavior about disk i/o. Have a nice day :) Thomas
