From Raspberry PI 2 Cluster Case pt1, I drew up a rough sketch with certain goals I set out to. They are,
- Able to fit in 6 RPI2 in a small, contained volume.
- Has to be stackable.
- Able to fit in a power supply and a 8 port network switch for the 6 RPI2.
- Able to cool off the cluster with no fan.
- Has to be cheap.
I then cut out an Acrylic panel at a near laser shop.
The panel have two big round holes for ventilation, 8 holes for RPI2 mounts, and 8 more holes for pillar screws.
Once you put pillars, it looked like this.
I put a giant square hole in the center to put a USB charger as power supply. You can see the two big round holes for heat ventilation.
At this point, I was terrorized with fact that I could not put a USB-to-MicroUSB cable to the center USB charger. You see the square hole is completely closed? I found that the panel blocked the USB charger’s USB socket, rendering the charger useless. What a bummer…
Of course, my happy story did not end there. I then put a RPI to see if it fitted in. To my disappointment, the mount was just too high. You see USB ports sticks to the upper level panel, and there is space underneath the RPI? That’s bad.
In fact, the mount was just too Long. I figured a mount should be around 4~5 mm in length. On top of that, I put one too many pillar screws. I had to use only the minimum number of them to maintain structure strength.
All in all, three problems.
- Entrance to USB charger.
- Appropriate Mount screw.
- Minimum # of pillar screws.
The Final Result
After Fixing three issues above, I now have this.
Those USB-to-MicroUSB cables are only 30 centimeters in length. They still stand out and take up quite a bit of space. Does anyone know where I can get a shorter cable?
Of course You can put the entire cluster on your desk.
I’ve run the cluster closed to two months so far. I’ve experienced neither heat issue nor performance hit. No single node has gone down while I’m running Apache Spark/Hadoop in cluster mode. It has been amazingly stable and easy to operate. Although there are few more issues I like to fix up later. (Especially the USB charger cable.)
Let’s move on to JAVA on Raspberry PI next time.