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.

  • mlfh@lm.mlfh.orgEnglish
    12·
    12 hours ago

    The grub command line options at the beginning of this article might help get your system booted without the memory deadlock, and then you can make further adjustments as needed: https://tierhive.com/blog/tierhive-howto/debian-13-minimal-guide-reduce-ram-to-38mb-and-disk-to-275mb

    Alpine is great for exactly this kind of thing, though, and I use it often in embedded environments where resources are at a premium. Just do some good reading up on it beforehand, since can be very different if you’re used to debian and systemd.

    • dan@upvote.auOP
      6·
      12 hours ago

      Thanks for the link!

      I’m trying Alpine locally in a VM with 256MB RAM, and so far so good. I got my app successfully cross-compiled using musl-gcc, rsync’d it over, and it starts on the VM with no issues. Now I just need to figure out all the stuff around it (like certbot) and do some more thorough testing. I use an Ansible playbook to deploy to the Debian servers, so I’ve got to update it to handle Alpine too.