The next two images show the front of the DS212 with the glossy plastic cover removed. It simply pops in/out without tools, and with it out of the way we see the two tool-less drive trays. To remove the trays you simply press the tab at the top labeled "PUSH" and pull out the drive using the attached handle. The drive bay design makes sure that each tray is aligned properly during installation, and when fully inserted they click to let you know the drive is connected.
The next shot shows the drive bay with the trays removed. You can see the simple PCB featuring a pair of SATA data and power connectors, positioned in just the right spot to match up with the installed drives. Additionally, we can see that the metal frame work of the drive bay is substantial enough to hold everything together, while also offering plenty of open area for the exhaust fan to work efficiently.
The images below show the two trays with 1TB Seagate drives popped in to them. Adding a drive to a tray is just as easy as getting the tray out of the enclosure, so if you need to swap drives at any time the whole process shouldn't take long at all. As a matter of fact, for this review I decided to remove the 1TB drives that Synology provided with the unit in order to test the system with the maximum capacity (currently) supported. With a pair of 3TB Seagate drives in hand, I timed the whole process to remove the existing 1TB drives and replace them with the 3TB models... Just under 1 minute!