Do not buy this product!
I bought this unit to solve my movie collection storage problem by consolidating all my movies into one HD with the mirror drive providing safety. The (scant) instructions tell you its all easy peasy. Don't believe any of this. One can only upload files larger than 5 Gb by connecting another hD directly into the Home Duo. But worse was to come. I needed to delete 1 single movie, and by doing so ALL my movies just disappeared ... TOTALLY master folder and all. By this time i had deleted all of them on my smaller HDs so lost the lot. Contacted WD, their response was "this is too complicated to handle via email, please phone us ... in the USA mind you!!! Unbelievable - no data recovery options given, nothing. This product is not fit for purpose. I waited about 4 weeks for delivery and spent the last 9 days mostly in utter frustration. A TOTAL waste of time and money