Mini Rack 002: Simple USB-C powered Pi K3s Cluster

[geerlingguy]

Description: My goal was to build a very basic mini rack Pi cluster, targeting a lower price with 1 Gbps networking and USB-C power. Using DeskPi's Pi 5 NVMe 2U mounting bracket, I can have a 4-node Pi cluster with NVMe SSD storage, and USB-C power delivery. I added on a 10" rack PDU on the back, to keep power organized.

Plug in a network jack, and an AC power plug, and away you go!

Full parts list (I earn for qualifying purchases...):

• DeskPi RackMate T0: $110
• DeskPi 2U 4x Raspberry Pi PCIe NVMe Mount: $100
• 4x Raspberry Pi 5 8GB: $320
• 260W GaN USB-C Charging Station: $25
• Tupavco 10" Mini Rack PDU: $45
• 1 ft 3 pack USB-C cables (x2): $20
• Mikrotik CSS610-8G-2S+in Switch: $110
• Mikrotik RMK-2/10 Rack Mount Kit: $15
• Monoprice Slimline Ethernet 6" 10 pack: $22

Total cost (brand new, not including tax/shipping): $767

[Andrew-Stevic]

FYI, the Mikrotik RMK link to Amazon goes to a page that no longer offers it for sale

[barrelltitor]

With a GaN charger won't the power communication happen whenever you reboot a pi causing everything to shut down for a sec?

[geerlingguy]

@Andrew-Stevic - D'oh! It's hard to find links to US stores with that part. I guess you can google and try to find one on Mirkotik's site.

[Andrew-Stevic]

@geerlingguy Yeah I found it on the Mikrotik site, just wanted to let you know about yours. I really appreciate this repo and all the mini home lab work you are doing. Awesome stuff

[sunsetblu3]

Just watched your video highlighting the Mini Rack & I've got to say - as someone who got into this particular flavor of hobbying, I love that you guys dropped this new set of projects. I've made my own magic mirror with a pi5, working on building a NAS next, and a bunch of other stuff inspired by awesome channels like y'alls. Much love & may yall stay blessed with finesse!~

[tuckr]

This looks awesome and I've tried to match the shopping list on amazon dot nl.
Edit: A great Dutch source for rpi's is Kiwi Electronics

[barrelltitor]

@geerlingguy What about the GaN charger question? I've been thinking of something like this but GaN chargers I've used before re-did their power communication every time I unplugged/powered off a device, so unplugging or powering off a pi means restarting the entire rack which is not really ideal

Are there any alternatives? Or are there specific GaN chargers that don't have this whole power delivery thing? Or maybe the other way around and only specific GaN chargers do this?

[jamesrshaffer]

@geerlingguy
I bought exactly the power supply you spec'd. When loading my Pi5 (again, exactly as you spec'd...) I used a USB stick to load the OS. RPi boot told me that my power supply was inadequate to supply enough power when booting from USB. It said it was limited to "3000". I don't know if that's milliamps or watts or what, but what is the issue? Seems the power brick you spec'd can supply lots more than 3 amps. I overrode the warning and everything worked fine. I set up the NvME to load, removed the USB drive and wow is that fast!.

Any idea on the power issue?

[geerlingguy]

@jamesrshaffer - You should be able to add usb_max_current_enable=1 inside /boot/firmware/config.txt and then it will allow the USB ports to use the full power from the PSU. If your drive uses a LOT of power, it could be an issue (or if you have multiple drives plugged in).

[jamesrshaffer]

Jeff, if there's another way that's better to ask you quick questions, let me know. I have a couple of questions:

1. What's that sheet of acrylic for on the Mini Rack?
2. If I want to install an RPi4, do I go ahead and install the daughter card even though I assume I can't use the NVMe slot?

[cdevelc]

With a GaN charger won't the power communication happen whenever you reboot a pi causing everything to shut down for a sec?

Yes, I think I am partly seeing this. Using the above 260w USB supply whenever I unplug one of my RPi5's from the USB-c the other one reboots. Seems to be reliable 24/7 power otherwise.

[barrelltitor]

@heytommyg More RAM never hurts. There's plenty you can do with the extra RAM, and if you find no current use for it you can always use it as volatile storage for things like plex transcodes

[geerlingguy]

@heytommyg - For the 2U Pi mounting kits from 52Pi, they have an NVMe slot in each kit, but you can choose to boot off microSD instead if you want (that's how I did it in my initial setup).

You can also connect drives through USB if you like (some people do external SATA 2.5" SSDs that way).