[GTALUG] block size for dd -- no difference

I was doing one of those occasional backup of my root SSD to HD. They are identical size, so sector by sector. I took this occasion to see if blocksize (bs=) matters. for i in {4,16,64,256}K {1,4,16,64}M; do echo ==== $i ==== dd if=/dev/sda of=/dev/sdi bs=$i sync done No difference. All did 117MB/s.