Just got my new cluster hat, who wants to help me get up to speed?

[Jason Henry]

Well, things started when I was cleaning out a desk drawer and found a forgotten stash of Pi Zeros. (two 1.2, two 1.3) and thought 'only way these will ever see use is if I cluster them', ...so, hat ordered.

Wasn't until I was at work the next day when the day slowed down enough that I could think about other things when it finally occured to me that the Zeros were still single-core and a pi3 (only spares I have free right now are 3Bs) with four of Zeros would still be outclassed by just a pi5 on its own, maybe even a pi4 depending on the application... So what do I do?

...that's right- jump the shark on the point of this (putting some otherwise unused parts to work) and decide I'll start acquiring some Zero2's. I have a local MicroCenter, they have some in-stock, it's not a time critical project, etc... ...they had four when I first checked, I already had one spare so just needed 3 more. MicroCenter still has a one/per restriction and I'm still a bit surprised I was only able to get one of those four before they all sold. So, two to go.

So, ...while I'm waiting for them to restock, I have other things to figure out...

1) pi3, pi4 or pi5? ...I have a couple projects that could stand a hardware refresh, so I could free up a 3B+ pretty easily unless there's significant reason to go with a pi4 (ie: power overhead). That said- 8g pi5 is, like, $5 more than an 8g pi4, so I guess my real question there is if a 3B+ would be better than a 3B, or if a pi4 would be better then any reason a pi4 would be preferred over a pi5. (ie: cooling). My thoughts being that a pi3 would likely be fine with ambient cooling, pi4 might be fine with ambient cooling so long as there's airflow in the area, pi5 will absolutely need active cooling.

2) power supply... Which I guess would be dependent on the resolution of 1), unless separate pi and hat power is something I should reconsider (if I could, I'd just add a PoE hat and take advantage of my preference and existing infrastructure, but I expect that's not a real option here?)

3) TBD

...

...

12) what the hell am I going to use this thing for?

Thanks in advance and looking forward to other people's thoughts,

-jason

[Ian Goldsmith]

Might be old but 

https://medium.com/@dhuck/the-missing-clusterhat-tutorial-45ad2241d738

isn’t a bad start. Not sure whats changed in the years since.

Some versions of kuberneetes should be possible for learning - k3s iirc.  The horsepower will never be the point - there isnt any. 

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[Jason Henry]

Yep, looks like that will be a fine starting point. or at least something to focus on until I get settled in ;)

I was actually thinking something along the lines of a Docker Swarm might be what I poke at first... I have half a dozen or so Pis that are generally always on but seldomly used (ie: OSMC, a pi-based NAS, octopi, etc) and my thought was to maybe reclaim some of that idle processing ability for other low-demand services- I've thought about piHole, maybe a local git with a network browser UI (if such a thing exists). I think my idea currently is to use the cluster as a central hub with the host pi orchestrating the whole thing. Attached Zeros as primary nodes then if things go well I'll look at adding those other devices as secondary nodes or translating those devices into containers to be managed by the swarm as a whole.

Or at least that's as much of a rough plan as I have currently. 

[Jason Henry]

So. As tends to happen- I start projects, I make a bit of progress, life happens, 'projects' go on hiatus, then months later I come back to them with vague recollections of where I was and what I was meaning to do next.

In this case- I got my ClusterHAT, got my first configuration built and functioning, and was in the process of thinking through the next steps.

ie: first build was with a pi3 and 4x OG Pi0's (2x v1.2, 2x v1.3) on top and a Suptronics x820 SATA<>USB below. The x820 has 5v USB that I tried using to power the Pi. It works, but with only 2 amps to work with... The pi3 and more than one pi0 node results in pretty constant power warnings. 

Step1 is power. The x820 also has a couple 2-wire pin headers for 5v supply and I think they're uncapped and have access to the full 4 amps from the wall-wart. Beyond that, I haven't decided but I'm leaning towards leaving the Pi on the x820 USB power and soldering a 2x screw terminal onto the clusterhats pads.

Step2 should probably be a fan. To this point, cooling has been just a couple cheap blue anodized aluminum heatsinks that were floating around my bench as I was assembling boards and standoffs. 'they can't hurt' I thought at the time, but I'm not sure that's true

Step3 is probably to swap in some Pi0 2's, I think. I already have 2 or 3 that need a home and there's a MicroCenter close enough that picking up a couple more shouldn't be too big of an issue. Those OG zeroes were painful running updates, especially having to do them sequentially considering the power restriction.

By Step4 I should have hardware pretty nailed down (I hope) to turn my attention back to software, which I haven't really started to crack yet. I'm pretty sure I need to turn my attention back towards CBRIDGE instead of CNAT, but I'm still not sure. I switched to CNAT thinking 'less DHCP reservations might be nice' but I'm not sure I won't be looking to add external devices to my cluster eventually. Pretty sure I'll stick with USBBOOT since I have all the local storage I could want. I think it currently has a 250g 2.5" hdd, I have a surplus of 1tb hdd's, and, again, MicroCenter relatively close if I decide to go ssd (and maybe add some surplus back to that 4 amp pool.

Step5 and beyond is completely uncharted for me and I could start a pretty solid wall of text with random thought fragments. Pretty sure I'll be going the Docker Swarm route as it seems to best fit my use case, even though I don't even have a firm grasp on what I hope to achieve with that, even. Thinking I might try consolidating things I've previously done (ie: 2011 MacMini running Frigate and MQTT, a Pi-based HomeAssistant stack... Not sure a Pi-cluster Docker Swarm would make a good Frigate host... But I have a bunch of low-power dedicated systems with pretty high idle-times... /EndRandomThoughtStream)

So. Anybody have thoughts about any of that?

[Peter Feeney]

Personally, you need to look at the max power requirements of each board and then choose your psu. 

Flaky supply to a RPI causes odd issues

So options on usage and abusage.

1. yes you can use docker swam

2. yes k3s is a great option too

If useing USBboot, you could have different boot images, and just changes pointers to images for booting.

I persoanlly use k3s and then have an OpenMPI boot image.

Another one I played with was using the Parallel computing in Wolfram.

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[Jason Henry]

Based of the figures in the FAQ- A pi5 with 4 zero2w's needs just a little over 4 amps(@5v), a pi4 drops that to just a bit under 4 amps. I'd expect a pi3 to continue that trend, perhaps with a larger margin. Still not sure it'll get low enough to also spin the hdd on the x820. But that's for later and easily solved with an upgrade to 5 or 6 amps. My main concern at this point is simply to get an adequate power path established.

I considered k3s as well, but just think Docker might be more viable for my use-case. I considered parallel-computing as well, but don't really have any large-data to process. Maybe if it could be a viable replacement for the Coral AI in my frigate build or something, but it just feels that several small containers that normally just sip the resources of dedicated hardware is a better fit.

Having multiple boot images is a factor for why I chose usbboot, but a minor factor after general avoidance of SDcard-usage.

[Peter Feeney]

If you have access to Argos or similar Lenovo are selling a 68W USB-C charger which looks to be a perfect fit! Also Raspberry Pi do a 45W USB-C PSU.

Not knocking Docker, My home lab has the following:

1) IPFire (firewall) Pi4 - 8gb

2) small 4 port hub with uplink

3) cluster hat on RPI4 with rpi v2 0's

4) nas rpi4 - 8gb (docker and NFS) with 2 x 1TB usb3 drives.

5) clacks(x220) on the base station is wired into the hub

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[Tim Breitberg]

following as I keep forgetting I have 2 of the v.2.x and such probably been on about it since 8086's release. Sometimes this ADHD kicks my ass.
Jason, post your success to inspire me to finish my builds.

[Peter Feeney]

@Tim Breitberg

When I have loads on I use an ADHD tool approach of just a small task but only 20 minutes of it then switch to the next task. The task list only shows me 3 or 5 items on the big list for the day (which only has 8 items on it). Based on the bullet journal and time management training.

Pete

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[Jason Henry]

I'll try to keep this in mind as I move forward and document accordingly.

As it stands, I have a MicroCenter close enough that it's not a completely unreasonable drive, so I've been keeping an eye on their headerless Pi Zero 2 W stock (currently 0, but +25 with headers :/  ). I'd prefer to upgrade all 4 at the same time, but we'll see. I think I have three, but I'd like to hold onto one for another project.

Other than that- I ordered a lot of screw-terminal headers and a 10 amp power supply that just arrived a couple hours ago, but my workbench is currently out of workable space, so I'll need to address that first. Maybe by then I'll have convinced myself that things will be fine plugging a 10a supply into the Suptronics x820 that came with the recommended 4a supply. On my way there I need to sort what I want to do about fans and some sort of testing enclosure that I can start mounting things to and in.