Copy original copies on external hard drive extremely slow and stuck

Hi,

I try to Putting original copies on external hard drive from my Lightroom CC.

The synch is so slow I sometimes can't tell if it still work. Regulary I restart Lightroom CC to see if the synch/copy to ext. HDD still work.

I have about 30k Images (~550GB) and only got 150GB ~8k Images stored on my HDD after 3 Days!!

Is there something I can do to speed up and to show me the sync still run?