I figured that this is a good experiment so I decided to build the expansion using an Atom-based mini-itx motherboard, 4GB of memory and a SATA raid controller. The controller would have 4 1.5TB drives plugged in to it in RAID 0. Yes, I know that RAID 0 offers no redundancy but I do have backups of my data so don't worry about it. The case is a generic case that is often used for audio devices. It's made of aluminum.
Given my love for LEDs and for blinking lights in general I decided to make it a bit more than just a box with hard drives in it. I used the HDD VU Meter that was posted a long time ago on bit-tech.net. I was lucky enough that the RAID controller already provided the pins for activity LEDs so I don't have to wire each hard drive separately.
I used chemicals to make my own PCBs. It's not difficult if you follow their instructions and a lot better and faster than using harmful UV lights, let me tell you. Here is one board, the exposed copper slowly dissolving away.
After I was done with all 4 boards I sanded them to remove the black film and made sure they were nice and shiny so that the solder would adhere better.
I bought a mini drill press that was stable enough to use a 1/32" drill bits. I heart that drill press.
All four boards assembled and ready to be wired.
Using a spare computer I calibrated the boards. To calibrate them you can use the instructions from the bit-tech.net site. Here you can see one of them in bar mode while the hard drive is writing a 10GB file.
To mount them to the case I built a mini-rack out of acrylic to hold them in place. Here it is:
I then drilled the metal case. Because drilling 40 holes that close to each other is not as easy as it sounds, I used a center punch hole to make sure my drill bit doesn't wander off and mess the holes up. Here you can see the LEDs of the 4 boards already aligned to the front of the case.
I used a CAT 4 ethernet cable to do the wiring for all the boards, power and LEDs to the RAID controller.
Here is the final result:
And now it's installed under my server in the rack I built specifically for my server closet:
Using Windows 2008 R2 Storage server for the atom-based computer and the iSCSI initiator software on my main server I am able to add an infinite number of these devices and all shared through the same server. Using a gigabit switch with jumbo packets support I get a very respectable 70MB/s-80MB/s transfer rate which is more than I could imagine.