NixOS on Btrfs+tmpfs

#1

Post by shiryel » Thu, May 05, 2022, 5:46 AM UTC

Re: NixOS on Btrfs+tmpfs

#2

Post by yjftsjthsd-h » Sat, May 07, 2022, 5:48 AM UTC

Neat:) I would never use btrfs myself[0], but very happy to see people exploring all variations of these ideas. The one thing that's starting to bug me though, as I read blog posts about installing nixos: why is the install process so imperative/non-declarative? Once the system is up, the whole thing fits in configuration.nix, but to get there we still have to use masses of shell commands. Is anyone working on bridging that last gap and supporting partitions, filesystems, and mounts (I think that's all that's left?) from nix itself?

[0] I lost 2 root filesystems to btrfs, probably because it couldn't handle space exhaustion. I'm paranoid now.

Re: NixOS on Btrfs+tmpfs

#3

Post by rrix2 » Sat, May 07, 2022, 5:52 AM UTC

yjftsjthsd-h wrote: post #2

Neat:) I would never use btrfs myself[0], but very happy to see people exploring all variations of these ideas. The one thing that's starting to bug me though, as I read blog posts about installing nixos: why is the install process so imperative/non-declarative? Once the system is up, the whole thing fits in configuration.nix, but to get there we still have to use masses of shell commands. Is anyone working on bridgi…

I have a fork of `justdoit.nix' https://github.com/cleverca22/nix-tests/blob/master/kexec/ju... which generates installer images with an auto-partitioning script and stub "configuration.nix" embedded in it with basically just enough of a system to get nixops or morph to deploy to it. it's kind of a pain to get that working the first few times since you have to wait for an image to bake and then test it in QEMU, and then make changes for nvme, etc, but it's brought up three systems now.

Re: NixOS on Btrfs+tmpfs

#4

Post by yjftsjthsd-h » Sat, May 07, 2022, 5:57 AM UTC

rrix2 wrote: post #3

yjftsjthsd-h wrote: post #2

Neat:) I would never use btrfs myself[0], but very happy to see people exploring all variations of these ideas. The one thing that's starting to bug me though, as I read blog posts about installing nixos: why is the install process so imperative/non-declarative? Once the system is up, the whole thing fits in configuration.nix, but to get there we still have to use masses of shell commands. Is anyone working on bridgi…

I have a fork of `justdoit.nix' https://github.com/cleverca22/nix-tests/blob/master/kexec/ju... which generates installer images with an auto-partitioning script and stub "configuration.nix" embedded in it with basically just enough of a system to get nixops or morph to deploy to it. it's kind of a pain to get that working the first few times since you have to wait for an image to bake and then test it in QEMU, and t…

Thanks! I'll have to give it a spin:)

Re: NixOS on Btrfs+tmpfs

#5

Post by viraptor » Sat, May 07, 2022, 5:57 AM UTC

> Most subvolumes can be mounted with noatime, except for /home where I frequently need to sort files by modification time.

That doesn't sound right. Noatime turns off recording of the last access time, not modification.

Re: NixOS on Btrfs+tmpfs

#6

Post by genghizkhan » Sat, May 07, 2022, 6:00 AM UTC

I would prefer to do this on zfs, for which there is a lovely installation guide on the openzfs docs site.

https://openzfs.github.io/openzfs-docs/Getting%20Started/Nix...

Re: NixOS on Btrfs+tmpfs

#7

Post by kaba0 » Sat, May 07, 2022, 6:24 AM UTC

genghizkhan wrote: post #6

I would prefer to do this on zfs, for which there is a lovely installation guide on the openzfs docs site. https://openzfs.github.io/openzfs-docs/Getting%20Started/Nix...

I can vouch for how good it works. Using it on my personal laptop.

Re: NixOS on Btrfs+tmpfs

#8

Post by pdenton » Sat, May 07, 2022, 7:21 AM UTC

viraptor wrote: post #5

> Most subvolumes can be mounted with noatime, except for /home where I frequently need to sort files by modification time. That doesn't sound right. Noatime turns off recording of the last access time, not modification.

IIRC, noatime is useful everywhere except /var/spool or /var/mail where certain daemons may depend on access time correctness.

Re: NixOS on Btrfs+tmpfs

#9

Post by nix23 » Sat, May 07, 2022, 7:22 AM UTC

yjftsjthsd-h wrote: post #2

Neat:) I would never use btrfs myself[0], but very happy to see people exploring all variations of these ideas. The one thing that's starting to bug me though, as I read blog posts about installing nixos: why is the install process so imperative/non-declarative? Once the system is up, the whole thing fits in configuration.nix, but to get there we still have to use masses of shell commands. Is anyone working on bridgi…

I loose every two years (when i test it again) a volume to btrfs, last time 2 month ago, with that simple "trick":

-Fill your rootpartionion as root with "dd if=/dev/urandom of=./blabla bs=3m"

-rm blabla && sync (we don't want to be unfair to such a fragile system)

-Reboot and end up with unbootable /

It's a mess, for a filesystem i would declare it as alpha stage.

Re: NixOS on Btrfs+tmpfs

#10

Post by londons_explore » Sat, May 07, 2022, 8:05 AM UTC

pdenton wrote: post #8

viraptor wrote: post #5

> Most subvolumes can be mounted with noatime, except for /home where I frequently need to sort files by modification time. That doesn't sound right. Noatime turns off recording of the last access time, not modification.

IIRC, noatime is useful everywhere except /var/spool or /var/mail where certain daemons may depend on access time correctness.

You can't depend on access time correctness... Because someone else can come along and grep through all your files and now they're all accessed right now.