I run dnstools.ws which lets you perform DNS lookups, pings, traceroutes, etc. from 25 locations around the world. Each location is powered by a VPS running Debian, running a C# service that’s compiled to native code ahead-of-time using Native AOT. It uses ~60MB RAM.
Six of the the locations are powered by tiny “NAT VPSes” (native IPv6 with shared NAT IPv4) that only cost a few dollars a year, sponsored by various server providers. These usually have 256 MB RAM and 4-5 GB disk space.
This is great with OpenVZ and LXC. Since they’re containers that share the kernel with the host, kernel memory doesn’t count towards the container’s memory limit. I’m using ~75 MB RAM on those systems: ~60MB for the DNSTools worker and ~15MB for everything else (sshd, systemd, cron, rsyslogd, and unattended-upgrades). Plenty of room left.
I also have a few KVM systems with 256 MB RAM. These are what I’m struggling with.
Debian 13 (Trixie) increased the minimum hardware requirements from 256 MB to 512 MB RAM. It seems like this is a hard requirement - When running on a system using 256 MB RAM, the installer complains about having too little RAM, and OOMs during the installation. Even with a successful installation (e.g. upgrading from bookworm to trixie), it kernel panics on boot: “System is deadlocked on memory”.
I could try debootstrap to bootstrap a basic system, or Clonezilla to clone a working disk image over the network, but I think I’d hit the memory deadlock too.
Does Debian have smaller kernel images for VM environments, that use less RAM? Or should I just give up on Debian for this use case?
Does anyone have a recommendation for another distro I should use? I’ve been considering trying Alpine. C# does support compiling to use musl instead of glibc, so that’s not an issue. I’m also not tightly-coupled to systemd and can get rid of it.
I can mount a custom ISO on the systems, so booting from an ISO isn’t an issue.
Thanks!
Edit: Alpine looks very promising - no issue installing it and running my app on a 256MB VM. This is probably what I’ll end up using.
Why not give Gentoo a try?
It natively require you to compile the kernel which is perfect because you get to drop all the drivers and features you don’t need.
Gentoo package manager also compile every package in the system which is very slow but it gives you lot of control over what features you want from each package. You’re no longer required to install X server just because one package provide GUI support.
End result is less memory for kernel and less memory for most other apps. 256 should be doable but just to be sure try running “sysrescuecd” which is based on gentoo. first to see if it would work
I’ve been using Linux for over 20 years and yet I’ve never tried Gentoo. Good idea. I’m not sure how well compilation would work on a 256MB system, but I could probably build a system in a VM locally then use Clonezilla to copy it to the production system.
Nitpick: precompiled kernels are now available as
sys-kernel/gentoo-kernel-bin, but you certainly can build your own (I’ve done that for two new machines in the past six months).It used to be, but isn’t anymore. Try booting the Gentoo minimal install image for your arch instead.