One of the frustrating behaviors of dd is that it provides no feedback about what it is doing. It does however provide a signal (USR1) that you can send to the process that will dump the current progress. Open a new terminal (I use screen) and type:
while true; do kill -USR1 `pidof dd`; sleep 2; done
(NOTE: if `pidof dd` doesn’t work for you, just use the process id directly)
Switch back to the terminal where dd is running and you should see:
9902751744 bytes (9.9 GB) copied, 732.883 s, 13.5 MB/s
9469+0 records in
9468+0 records out
9927917568 bytes (9.9 GB) copied, 734.914 s, 13.5 MB/s
9496+0 records in
9495+0 records out
9956229120 bytes (10 GB) copied, 736.941 s, 13.5 MB/s
updating every couple of seconds.