Synology Launches RC18015xs+ / RXD1215sas High-Availability Cluster Solution
 

Synology is no stranger to high-availability (HA) systems. Synology High Availability is touted as one of the features that differentiate Synology's NAS units from other vendors' for small business and enterprise usage. Put simply, Synology HA allows two NAS units (same model) to be connected to each other directly through their LAN ports, while also being connected to the main network through their other LAN ports. One of the NAS units is designated as the active unit, while the other passively tracks updates made to that unit. In case of any failure in the active unit, the other one can seamless take over without any downtime.

http://www.anandtech.com/show/9367/s...uster-solution