Synology has a storages system called SHR !
SHR is an automated RAID management system that makes storage volume deployment easier than traditional RAID systems. SHR will allow users to handle RAID management, expand storage, and maximize storage capability even if they do not have a fine grasp of various RAID levels. SHR allows for 1-disk or 2-disk worth of redundancy - meaning the SHR volume can suffer up to two disks lost, and the data volume will still be available for use. Note that a RAID volume (either Classic RAID or SHR) is not a backup system.
I have this old Synology Cube Station CS407e that I in this video set up from the scratch.
Links to get a Synology NAS - http://amzn.to/1Urt41t