For economy and convenience I would simply use an external USB 3.0 HDD.

For example, the Hitachi 4TB external HDD is cheaper than the internal HDD equiv. So, rather than run the risk of pulling internal HDD in and out of the unit (probably a few unintended consequences in doing this), I just use regular Sooloos backup to ext. HDD.

For 'belt and braces' I also run a full native export to another HDD.

FWIW I am pretty sure that RAID is not really designed for frequent swaps. The reconcilliation must get messy.


Rgds,
Nick