Comment by herpderperator | Hacker News Reader

Comment by herpderperator | Hacker News Reader

What a coincidence, I just finished setting up my 64GB RAM / 2 TB storage Raspberry Pi 4 PoE cluster tonight (only 1 power cable!): https://www.dropbox.com/s/um5mjt8bucfkrbk/picluster.jpg?dl=0

I was really impressed that I got line speed Ethernet between the Pis, 112MB/s doing a wget of a 1G file from one to another. Things have improved a lot since the original Raspberry Pi from 2012.

I need to figure out how to get the 8th Pi working though, since I'm using one of the PoE ports to power a Mikrotik that I'm using as a wireless bridge onto my existing broadcast domain. Technically I don't need the bridge, since each Pi can connect to my wireless AP over 5GHz 802.11ac just fine, but it feels nicer to funnel upstream data through one point. More importantly, it reduces WiFi collisions since there wouldn't be 8 devices broadcasting simultaneously and interfereing with each other (especially at those close distances) if they all needed to download something from the Internet at the same time... like a Docker image for a Kubernetes deployment :)

Nice project! I just started researching the pieces I need to build something similar. What kind of PoE hat did you use? I was also thinking of having one of the PIs have also an SSD with bootp/dhcp and let the others boot with PXE.

I had been thinking of building a PIs cluster for a while now and I was looking with interest at the turingpi board project [1] they are taking preorders for the second batch if anyone is interested. But I would like nodes with more than 1GB of RAM so I guess I'll have to wait for that.

[1] https://turingpi.com

This is the PoE hat I used - I specifically chose it because of its low profile and fanless design: https://www.amazon.com/gp/product/B07WD7HXSQ/

Have you tried to experiment with 802.11s and mesh networks to remove some of these Ethernet cables by any chance? I'm looking into some "advanced" router features these days, and I was surprised that there is a standard for this, although it seems badly supported. That would seem like a good option for a more flexible (in terms of networking) cluster if the nodes are that close to each other that wireless networking shortcomings aren't much of an issue.

Of course that's only the theory...

I couldn't tell by your question if you were referring to the Pi cluster or asking an unrelated question about 802.11s mesh clusters... :)

Here are my answers for both:

Pi cluster: meshing won't save any additional wires here since there is already a wireless bridge set up (between the black Mikrotik device pictured, and an off-camera Mikrotik wireless router.) I chose to wire the cluster simply to guarantee a reliable connection within the cluster. You can absolutely use a Raspberry Pi over WiFi without an Ethernet cable, it would just be a less reliable connection (jitter, congestion), and then of course it would have to be powered conventionally rather than via PoE.

General 802.11s meshing: If all you want is fewer network cabling in your home specifically between switches and access points, then it could certainly help. However, the best choice network-wise is almost always a proper deployment with a central router and several APs (broadcasting the same SSID) wired back to it.

I guess I was curious about both, thanks for yours answers! I hadn't thought about PoE, having never used it myself, so indeed at one cable per device there's not much more to do.

That looks gorgeous.

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