nixos/swraid: enable it by default

[JohnRTitor]

It is detected automatically now according to #343760 (comment), so enable it by default

Things done

• Built on platform(s)
  • x86_64-linux
  • aarch64-linux
  • x86_64-darwin
  • aarch64-darwin
• Tested, as applicable:
  • NixOS test(s) (look inside nixos/tests)
  • and/or package tests
  • or, for functions and "core" functionality, tests in lib/tests or pkgs/test
  • made sure NixOS tests are linked to the relevant packages
• 24.11 Release Notes (or backporting 23.11 and 24.05 Release notes)
  • (Package updates) Added a release notes entry if the change is major or breaking
  • (Module updates) Added a release notes entry if the change is significant
  • (Module addition) Added a release notes entry if adding a new NixOS module
• Fits CONTRIBUTING.md.

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[arianvp]

The swraid module was pretty broken last time I checked. It shipped with a bunch of systemd services that try to call things in /usr and /opt etc. Has this since been fixed?

[arianvp]

Yes still seems to pollute the host witch a bunch of systemd units that are downright broken.

This needs to be fixed IMO.

[arian@utm:/etc/systemd/system]$ systemctl cat mdmonitor.service 
# /etc/systemd/system/mdmonitor.service
#  This file is part of mdadm.
#
#  mdadm is free software; you can redistribute it and/or modify it
#  under the terms of the GNU General Public License as published by
#  the Free Software Foundation; either version 2 of the License, or
#  (at your option) any later version.

[Unit]
Description=MD array monitor
DefaultDependencies=no
Documentation=man:mdadm(8)

[Service]
Environment=  MDADM_MONITOR_ARGS=--scan
EnvironmentFile=-/run/sysconfig/mdadm
ExecStartPre=-/usr/lib/mdadm/mdadm_env.sh
ExecStart=/nix/store/2hh5ld6cglkr59rx6h8w3z20qb0pbyvg-mdadm-4.3/sbin/mdadm --monitor $MDADM_MONITOR_ARGS

$ systemctl cat mdcheck_continue.service 
# /etc/systemd/system/mdcheck_continue.service
#  This file is part of mdadm.
#
#  mdadm is free software; you can redistribute it and/or modify it
#  under the terms of the GNU General Public License as published by
#  the Free Software Foundation; either version 2 of the License, or
#  (at your option) any later version.

[Unit]
Description=MD array scrubbing - continuation
ConditionPathExistsGlob=/var/lib/mdcheck/MD_UUID_*
Documentation=man:mdadm(8)

[Service]
Type=oneshot
Environment="MDADM_CHECK_DURATION=6 hours"
ExecStart=/usr/share/mdadm/mdcheck --continue --duration ${MDADM_CHECK_DURATION}

[ElvishJerricco]

@JohnRTitor Huh, I think I've made a mistake. I thought that this was only disabled by default for systemd stage 1, but in fact it's disabled across the board by default since 23.11 (scripted and systemd stage 1 and even stage 2). Given that it's already been disabled by default for two releases, I think we can just leave it as is and close this. Do you agree? I apologize for the confusion.

@arianvp Yes it seems there are a number of problems with our swraid module.

• Missing mdcheck script #332096 (fixed by swraid/mdcheck: add mdcheck timer for swraid device scrub #204713)
• systemd.initrd.enable requires manual raid configuration instead of using udev #210210
• Since systemd-251.3 mdadm doesn't start at boot time #196800

We probably need someone to go through and do some serious fixing up on the module, including the PR in that first bullet point. But that's unrelated to this PR.