Let me show you a little trick with the pv tool.
What is pv ? Pv is tool which can monitor the progress of data through a pipe.
apt-get install pv
Here is a simple example
dd if=/dev/zero bs=1M count=512 | pv -s 512M | dd of=/tmp/512M
512+0 records in60.5MB/s] [==========================================================================> ] 96% ETA 0:00:00 512+0 records out 536870912 bytes (537 MB) copied, 6.27769 s, 85.5 MB/s 512MB 0:00:06 [81.6MB/s] [=============================================================================>] 100% 1048576+0 records in 1048576+0 records out 536870912 bytes (537 MB) copied, 6.27816 s, 85.5 MB/s
If we make hard disk clonning, we can use
pv -tpreb /dev/sda | dd of=/dev/sdb