This is an older reliable USB or Firewire Raid Array for desktop
I have used this for 2 years now and no problems.
Comes with 4: 2TB Drives giving you 5.44TB of usable space. The drive is cleared and formatted ready to go. There will be no need to install drobo software its maxed out at 2tb per bay. and all you need to do is maintain the drives if there is ever a failure.
More drive info https://docs.google.com/spreadsheets/d/10XXasbZFC3Y0rLaYYqP-6tskfYhZ6uce-H1aspJ6WqE/edit?usp=sharing
Is compatible with the DR00D-E witch will turn it into a NAS.