That is simply a low power linux box running samba.
It requires all the drives to be identical, you can not change or upgrade the configuration (true of just about all RAID arrays), and if you have a drive fail but can not get the EXACT same drive to replace it later (model, and firmaware) you will suffer a performance loss using the device.
It's important that if you build a RAID array that you purchase spare drives while you can. You also have to buy the maximum configuration you will ever use with it, at the time you build.
Things are changing quickly, though. You can throw a drive of any size at a Drobo from any manufacturer, and upgrade accordingly as you wish. The same might
be true (with limitations?) with some of Infrant's RAID(like) products, also.