[throwawaaarrgh]

This is actually much better because nbdcopy can handle sparse files, you can set the number of connections and threads to number of cores, you can force a flush before exit, and enable a progress bar. For unencrypted drives it also supports TLS.

[verticalscaler]

If you really want a progress bar chuck in a 'pv' somewhere into the command posted at the top of the thread.

[rwmj]

Or add nbdcopy -p option :-)

[brokenmachine]

And "dd conv=sparse" to fix the other problem.