This is my trusted Terastation WS rack mount. I could not longer stand the old operating system so i installed an external SSD and installed Openmediavault. runs perfectly on the Atom D510 cpu that is on this unit.
it includes 4x ST4000NC000 4tb drives configured for Raid 5 giving you about 12tb of storage, this can be changed to other Raid configurations for more space. configuration tests the drives daily for S.M.A.R.T. issues. all clear
Openmediavault was installed with an automated Backup program and you can install more plugins such as a web based file manager, your own dropbox. the system runs on an external SSD i currently have stuck to the side, you can move this.
of course you could get the USB drive from Buffalo and reinstall their system but this was a Windows NT based setup that was very limited in capabilities.
This device is rack mountable but i do not have the rails or the front cover, the drives all have their caddies, see pictures. drives alone are worth the price. this served me perfectly for the last year or so. compare to a 12tb nas using raid 5 and you will see that this is a bargain.