I reviewed the DiskStation DS710+ recently, saying it was the first dual-bay NAS server to get scalable storage when coupled with an expansion unit. That unit is now available for around $500.
Synology announced Monday the Synology DX510, a five-bay expansion unit that can be used with either the DS710+ or the DS1010+ DiskStation NAS servers. According to Synology, the DX510 unit can increase the capacity of supported NAS servers up to an additional 10TB.
This means the RAID volume on the main DiskStation can be expanded directly without having to reformat the existing hard drives. If users choose to use the DX510 as a separate volume, the expansion unit will function as a backup destination.
The Synology DX510 is about 2.5 times the size of the DS710+ and connects to the Synology DiskStations via a custom-designed eSATA cable. Synology claims that this proprietary cable ensures a reliable connection and maximum throughput. The cap speeds between the NAS server and the expansion unit are that of the SATA 2 standard: 3Gbps.
Though I haven't had any hands-on experience with the DX510, the physical size of the unit suggests it's only suitable for business use. It's too bad that regardless of how many hard drives you want to use with it, the DX510's shape and size remain the same. It would be better if it was made of many sections that could be assembled as the amount of hard drives increases, or attached to the main NAS server in such a way that the setup remained a single hardware unit.
Still, for capacity-hungry environments, the Synology DX510 seems to be a great solution to quickly and significantly increase the amount of storage on your NAS server without any interruption.