up for consideration is my EX4100 that i used with my server for about a year, its been in storage since. time to give it a new home.
it does not contain any drives. load your own. you can use different sizes. i used a 10tb, 3tb,2tb and a 1tb
I used it in the raid config where it duplicates data among several drives so if one drive fails, the data is not lost.
this is a quality product, unlike drobo. if you are shopping for a RAID/NAS drive, avoid drobo.