Myself i'm running a instance for two people in a pretty small lxc container on my home server- 1vCore, 512MB of ram and 8GB storage. Currently it utilize around 5% of CPU, ~250MB of ram (+260MB of swap), and ~2GB of storage (nearly 50/50 picts/postgres), in terms of network traffic i see average of 20kb/s, depends how many communities are you subscribed for.

My homeserver is running on i3-4150, 16GB ram and a couple of ssds, using Proxmox VE as hypervisor

edit: typo

To answer what I think you are getting at lemmy scales based on two things:

1. Database size (and write volume) scales mostly on what communities are being federated to you. Unless you are .world the volume of remote content is going to massively outweigh local content. On my (mostly) single-user instance I have found this to be the same with Pictrs as well, as it is mostly eating storage to store federated thumbnails.
2. Database read load scales mostly on the number of users you have. For a single-user instance this is pretty minimal. For an instance like .world (with thousands of users) I imagine it is significant and scaling postgres to have read-only replicas to scale this load.

~18 hours ago I wrote

My instance has been running for 23 days, and I am pretty much the only active local user:

7.3G    pictrs
5.3G    postgres

I may have a slight Reddit Lemmy problem

As of right now

7.5G    pictrs
5.7G    postgres

So my storage is currently growing at around 1G per day, though pictrs is mostly cached thumbnails so that should mostly level out at some point as the cache expires.

To answer your stated question: I run an instance on a mini PC with 32G of RAM (using <2G including all lemmy things such as pg, pictrs, etc and any OS overhead) and a quad core i5-6500T (CPU load usually around 0.3). You could probably easily run Lemmy on a Pi so long as you use an external drive for storage.

AFAIK even a rpi zero can serve a lemmy instance just fine.

...

i'm currently hosting an instance for about 20 users on a dual-core epyc-7002 based cloud vm with 2 gb of ram and currently a 50 gb ssd volume. memory tends to sit around halfway and total disk usage is 14 GB, of which it's 4.5 GB for the picture server and 2.3 GB for the database for now, i'm monitoring both in case upgrades are needed. cpu usage is quite low, usually sits between 5-10% and never went above 25%. it was the highest during a spambot attack when they tried to register hundreds of accounts -- speaking of, enable captcha (broken on 0.18.0) or set registrations to approve-only.

i'm paying about $10-15 per month currently, which includes a cache to keep the instance snappy.

Storage seems to be the main requirement, so even a raspi4 should be fine, though you'll want 4gb ram, you just want a large ssd attached somehow.

Iirc it doesn't really like nfs either.

Mine is running on a low performance VM on my MiniPC under my bed lol. I've had absolutely no lag or errors. No problems at all very smooth.

It's pretty lightweight. I've given each container 1/3Gi of memory and 1CPU limit with low requests. Utilizing kubernetes HPA to scale containers under load up to 4 replicas. It only scales when a user takes large actions (subscribing to hundreds of new to the instance communities at once). But once the initial federation begins it seems to quickly scale back down. The biggest bottleneck is pictrs since it is stateful.

So far the database and pictrs is only about 2Gi of storage but I've allocated 25Gi to each since I have a lot to spare at the moment.

I have to play with the HPA more since I'm not happy yet with my settings. I have 2 users and 1 bot on my instance.

I'd like to start contributing to Lemmy's codebase so I wanted to host my own instance to learn the inner workings.

My postgres is a single replica at the moment but I may scale that if stability is becomes a problem.

I'm running mine (ani.social) on 4 cores and 16gb RAM for 17 users as of now. There isn't a lot of posts/comments coming from us yet but there's a couple of images uploaded already.

The current load average is only 0.10, postgres db is at 1.6 GB and pictrs is only at 430 MB. The database has been growing a lot faster than expected though but it seems manageable.

I'm running my instance as a containerized app on an i9-12900H, 64gb ddr4 ram, a 128gb Intel optane as a swap drive (my mobo maxes out at 64gb ram), and on a SATA SSD. My bottleneck is my internet which is stuck on 5g home internet. Serving. Any service behind cgnat has been a challenge, but thanks to zero tier and a vps reverse proxy, it's been possible.

Mine is running on a VPS with 1vCPU and 1GB of RAM, it is mostly okay except for going OOM on occasion. Luckily it’s just me in this instance right now lol. You may want to opt for more RAM depending on your planned usage tho.