So from what I understand once a file is >0 that you can't set nodatacow.

I'm playing around with cryptocurrency and the current one downloads the whole blockchain and it's at 65GB and growing. I think the growing part is the problem. That and it's being stored on /home which is a spinning disk not an SSD like the system disk. 

I'm seeing a lot of IO wait in glances and the system is sluggish even though CPU and memory usage is relatively low.

Ideas?

Thanks,
Richard