Raspberry Pi Cluster, Part 2 - Assembly

18 Sep 2021

• Raspberry Pi Cluster, Part 1 - Hardware
• Raspberry Pi Cluster, Part 2 - Assembly
• Raspberry Pi Cluster, Part 3 - Operating Systems
• Raspberry Pi Cluster, Part 4 - Jekyll and Docker
• Raspberry Pi Cluster, Part 5 - Kubernetes
• Raspberry Pi Cluster, Part 6 - Dynamic DNS
• Raspberry Pi Cluster, Part 7 - SSL
• Raspberry Pi Cluster, Part 8 - Automation

Here was the bit I was looking forward too, actually sticking all the bits together to build the Raspberry Pi cluster. It’s a pretty straight-forward process, it’s just a case of following the instructions - a bit like Lego.

Start by bolting the Pi’s onto the acrylic layers of the case. At this point, stick the heatsinks onto the Pi’s chips as it will be obviously harder to do this later down the line.

Using the case kit stand offs, attached the layers together to build the Pi stack (there must be a gag in there somewhere).

Finally attach the mini CAT5 cables to the switch and the USB cables to the powered hub. That’s, err, pretty much it.

Major problem No. 1

Every was going great, until I turned it all on. The timeline of the posts goes a little out of order here, as I didn’t find this problem out until I had created the operating system images, but it makes sense to talk about this here in this post.

The problem was that only two of the Pi’s turned on, the other two kind of flickered on and off, but mainly stayed off. Then one of the good Pi’s turned itself off and one of the dead ones sprang into life. And so on.

To be completely honest with you, I had a feeling that the powered USB Hub that I dug out of junk cupboard might not cut the mustard. Turns out that was the case, it simply couldn’t supply enough power for all of the Pi’s to be on at the same time.

The power solution

What I needed is a power supply that is designed to delivery at least 2A on each port simultaneously and a quick search turned up the Anker PowerPort. This is much more suitable to powering the Pi’s. Now all the Pi’s can run happily, even when under a high load. Problem solved.

As the new power supply has 5 ports, that left a spare port and that got me thinking. I wondered if I could power the Netgear switch via USB as well? Another quick search later and it turns out you can!

Now I only need one power cable for the whole cluster and all the ports on both the PSU and the switch are filled. The whole thing looks better and that makes me very happy.

Here was additional shopping list:

• Anker USB Charger PowerPort 5 (Amazon)
• USB Type A Male to DC Plug Barrel Connector (Amazon)

This added another £30 to the hardware budget.

SPOILER: This STILL isn't the final setup. There are more updates needed, but I'll cover that in a future post.

Now it’s time to work out what I’m actually going to do with this thing.

Next, Part 3 - Installing the operating systems