Rack ‘Em Up (Story Time. Skip to Pt.2 for the gritty)

There I was, fitzing around with my new server rack, wiring up my 24-port L2 switch... when the realization dawned on me... I don’t have enough connections to my network switch.

After all, what kind of server rack doesn’t have TONS of patch cables coming out the wazoo? A weak, pathetic excuse for a rack, that’s what. And I was determined not to have a weak, pathetic excuse of a rack. Nay. My rack would be muscular, and NETWORKED.

So of course I decided to build a server cluster — using single board computers (although at the time it wasn’t obvious to use SBCs).

Money Shot

What a Cluster F***

Thus, my research began. I searched the googles high and low for information on server clusters. “How can I maximize my rack space AND fill up my ports?”, I asked myself. Good question. At first, I wanted to go full cluster and try my hands at mITX blade servers. Bad idea.

I mean, the idea is good, but I’m not made of money. This server already put me in the hole for around $3k, and I’m just a student, damn it. I kept harping on that mITX blade server idea for a good two months or so, until I finally gave up the quest. It did present me with some interesting concepts along the way, however...

It’s So Small

That’s what she said. Ahem. During my googlization, I stumbled across some brilliant server cluster builds, ranging from the grotesquely large, to the obscenely expensive. Most of the setups I saw, looked really cool, sure; but they all seemed to be missing something.... “hotswap-ability”.

A clear picture of what I wanted to build, was formed in my head.
It had to be small. It had to use minimal power draw. It had to be PoE friendly. It had to be expandable. And most of all, it had to be hotswappable. Single Board Computers to the rescue! Now, I had to figure out how I wanted to mount them.

Hot-swap Or Not

Early on in my foray to building a server rack, I made sure that everything I did was modular — or as close to modular as I could get it. One such aspect of servers that I absolutely loved, was the ability to hot swap hard drives in/out of most server cases and storage arrays.

Three storage arrays and a few server chassis‘ later, I put my knowledge of drive caddies to good use. I knew now how I was going to get my SBCs mounted — why, I would just use a case with hotswap drive trays to create a server cluster!

Easier said than done, of course.

The Price Is Right

Six. Months. Later.... Nerve wracking. Brain wrecking. I just couldn’t find the right case, at the right depth and RU size, at the right price, to fit my needs of a server cluster.

It needed to be CHEAP. It needed to be hackable. It needed to be CHEAP.

Nothing I found online met my needs. Sure, I could buy a server chassis like that from Norco, or Supermicro, or Rosewill, but... those be EXPENSIVE. And most of them are full sized cases in length. I only had 10 inches of space to work with. That’s what she said.

Finally after much googifiying and eBay hunting, I believed I had come across THE ONE. It was a fine specimen, to be sure; sleek metal edges. Hefty, sturdy. Used but, not damaged. Cheap, but not a floozy. It had class, it had stamina. It had trays included.

It was a NetApp DS14MK2 Disk Shelf.

Looking back, I probably should have looked closer. I should have done more research. But, as with all things we fall in love with, I was blinded by my need, nay. My desire — for a cluster of servers. I thought that this handsome DS14MK2 could give me what I yearned for. So I bought it, and waited my delivery eagerly.

Boy, was I wrong.

Pt. 2 — The Gritty Details

Cut My Life Into Pieces

This was it. This was my last resort. Everything I had done up until now, all the time and money and sweat and googleringadings I had done, boiled down to this NetApp DS14MK2. See, when I bought it, I had believed I would be capable of simply removing the front half — the drive tray cage half — from the rest of the chassis. Then I’d simply... pop the drive caddies in, along with my mini pc’s, and voila! How naive.

The DS14MK2 practically laughed at my naïveté. It knew — it knew that it could not be split in half. And I had not the willpower, nor the tool power, to cut him in half. So I did the next best thing: I gutted the little m@#&^f#&$#ker like a fish.

• Step 1: First, I had to pop the rivets holding the innards in place. And pop the rivets I did. Oh boy, I did. Using a handheld drill, I drilled right through all the rivets on that smug disk array’s ... array. This let me access the plastic trays used to slide the hard drive caddies in. There were two plastic trays, one top and one bottom. I pulled those out gently — these were my pearls. I fished around inside to see if there was anything else I needed. There was not. I dumped the rest.
  
  Reference Photo
  
  
  
• Step 2: Now I had my all important trays, I needed to put them into something more... accomodating. Right away I knew that I would need a similar 3U height case, but only ten inches in length... tough to find. And find, I did not. So I built my own case! Hehehe. I was able to locate a 3U sliding cabinet and a plain ‘ol 1U solid rack shelf, both exactly 10” in length.
  
  
• Then I gutted the 3U cabinet, and kept just the top half.
  
• Then I grabbed the 1U shelf, and the 3U Cabinet-Top-Half, and just... smushed them together. Literally. With a mallet. And I stepped on it. With my feet. And more mallet smushing.
  
  And so, a new 3U case was born. What an ugly child it was.
  
  Reference Photo
  
  
  
• Step 3: Attaching the DS14MK2 plastic tray sliders to the inside of my Franken-case. This proved a bit tricky, since I had to do a lot of hole drilling into the new-fangled case. But it was made a lot easier due to the plastic trays having mounting holes already, so I just placed them inside, marked the holes with a marker, and drilled away. Drill baby, drill!
  Note: I did have to use some M3 standoffs underneath both plastic trays in order to get everything to fit at the right height. Also I used some steel epoxy putty to keep all the nuts and bolts firmly bolted in place.
  
  Reference Photo
  
  
  
• Step 4: Now with the case pretty much complete, I fit it into the rack and.... crap. I needed a backplane. After much hemming and hawing, I finally settled on a “ghetto”-fabulous method of attaching each drive caddy to a “backplane”... that is, I used a 3U blank keystone patch panel. Bent gently on the sides to create “rack ears”, and then drilled some holes onto the side of the chassis and bolted the patch panel into place. This allowed me to attach RJ45 female coupler keystones and utilize them as pass-through connections via RJ45 patch cables internally, and route everything out the back with more RJ45 cables (6ft) to my PoE injectors lower on the rack.
  
  Reference Photo
  
  Reference Photo
  
  
  
  

  Watch Out For the POE POE
  

  Now that I had everything securely mounted in the rack, I needed to get power AND Ethernet to each drive caddy / node. PoE to the rescue! This was a fun part of my build. First, I bought a few 4-port Gigabit PoE Injectors, 48v.
  
  Since each R-Pi consumes around 2 amps of current (depending on the usage), I didn’t want to overload the POE system with something like a 16-port PoE switch or one big PoE injector. That’s why I opted to daisy-chain multiple PoE injectors, so each “block” of PoE would be able to provide the rated amount of amperage for every four (4) nodes.
  
  The PoE injectors get their juice from the Mac Daddy 48v 7.2amp 350watt switching power supply. Since by this point I was salivating at the mouth to get my server cluster up and running, everything gets mounted with 2” heavy duty Velcro. Yea, that happened.
  
  Since they’re daisy chained (via 2.1mm barrel DC plug jacks), I can easily swap them out if needed, and I also have enough space for a second 48v PSU if needed as well.
  
  Close Up of PoE Injectors
  
  Front view of PoE Daisy chain system
  
  More PoE Daisy Chain
  
  
  ***
  
  
  Continued on new comment thread. . . (FU Reddit).

Buy rack shelves and put them in your rack?
https://www.amazon.com/Odyssey-ARS1-Space-Shelf-Accessory/dp/B0002DV0G8

I use these:

https://www.amazon.com/Odyssey-ARS1-Space-Shelf-Accessory/dp/B0002DV0G8/ref=sr_1_1?ie=UTF8&qid=1477967657&sr=8-1&keywords=odyssey+1u+shelf

Works great for non-rack stuff.

When I build new racks with equipment, I typically install 2. One to put my tools, tape, etc on and the other for my laptop when configuring devices.