I previously used a single eSata socket which was seen by the DS213 + NAS as an "external" device. With the DX213 expansion, additional disks are seen as internal volumes as well as the disks of NAS. The only limitation is that a priori is that it is not possible to make a RAID volume between the disks of NAS and those of the extension (no RAID5 so). The assembly of disks is not quite the same as a NAS DS213 +: there is no drawers "rack" (hot) accessible from the front panel. We must open the case closed by screws to insert the discs there. This still remains very simple and does not have any particular problems. I am completely satisfied with this product that allowed me to add two more drives in my NAS DS213 + simply and benefiting from the expertise of the brand Synology.
