nixos/profiles/zfs.nix

   1 { pkgs, lib, hostName, ... }:
   2 {
   3   # none is the recommended elevator with ZFS (which has its own I/O scheduler)
   4   # and/or for SSD, whereas HDD could use mq-deadline.
   5   services.udev.extraRules = ''
   6     ACTION=="add|change", KERNEL=="sd[a-z]*[0-9]*|mmcblk[0-9]*p[0-9]*|nvme[0-9]*n[0-9]*p[0-9]*", ENV{ID_FS_TYPE}=="zfs_member", ATTR{../queue/scheduler}="none"
   7     ACTION=="add|change", KERNEL=="sd[a-z][0-9]*", ATTR{../queue/rotational}=="0", ATTR{../queue/scheduler}="none"
   8     ACTION=="add|change", KERNEL=="nvme[0-9]*n[0-9]*p[0-9]*", ATTR{../queue/rotational}=="0", ATTR{../queue/scheduler}="none"
   9   '';
  10
  11   boot.supportedFilesystems = [ "zfs" ];
  12   boot.initrd.supportedFilesystems = [ "zfs" ];
  13
  14   # Using ZFS together with hibernation (suspend to disk)
  15   # may cause filesystem corruption.
  16   # See https://github.com/openzfs/zfs/issues/260
  17   boot.kernelParams = [ "nohibernate" ];
  18
  19   # Stable enough, clearer, and faster than the default /dev/disk/by-id
  20   boot.zfs.devNodes = "/dev/disk/by-partlabel";
  21   # Not useful so far.
  22   # See also https://github.com/NixOS/nixpkgs/issues/62644#issuecomment-1479523469
  23   boot.zfs.forceImportAll = false;
  24   # More resilient for remote hosts,
  25   # though it may call zpool clear.
  26   boot.zfs.forceImportRoot = true;
  27   boot.zfs.requestEncryptionCredentials = lib.mkDefault [ "${hostName}/root" ];
  28
  29   boot.zfs.enableUnstable = false;
  30
  31   # Enables periodic scrubbing of ZFS pools.
  32   services.zfs.autoScrub.enable = true;
  33   services.zfs.autoScrub.interval = "Sun *-*-08..14 00:15:00";
  34
  35   # According to zpool(8), for consumer hardware
  36   # periodic manual TRIM is preferred over the automatic TRIM
  37   # that ZFS implements.
  38   services.zfs.trim.enable = true;
  39   services.zfs.trim.interval = "Sun *-*-01..07 00:15:00";
  40
  41   # Hide ZFS mountpoints from gio, hence nautilus or caja
  42   systemd.services.zfs-mount.postStart = ''
  43     /run/wrappers/bin/mount -t zfs | cut -f 1 -d ' ' |
  44     xargs -n 1 -r -t /run/wrappers/bin/mount -o remount,x-gvfs-hide
  45   '';
  46
  47   environment.systemPackages = [
  48     pkgs.lzop # For remote syncoid
  49     pkgs.mbuffer # For remote syncoid
  50     pkgs.sanoid
  51   ];
  52
  53   # Force zpool import, even if the disk has not been exported,
  54   # (ie. still imported onto another computer).
  55   systemd.services."zfs-import@" = {
  56     description = "ZFS import pool: %I";
  57     unitConfig = {
  58       ConditionPathIsDirectory = "/sys/module/zfs";
  59       StartLimitIntervalSec = 0;
  60     };
  61     after = [ "systemd-modules-load.service" ];
  62     path = lib.mkBefore [ "/run/booted-system/sw" ];
  63     serviceConfig = {
  64       Type = "oneshot";
  65       RemainAfterExit = true;
  66       PrivateTmp = true;
  67       SyslogIdentifier = "zfs-import@%i";
  68       Restart = "no";
  69       ExecStart = pkgs.writeShellScript "zfs-import" ''
  70         pool="$1"
  71         set -eux
  72         zpool import -lFd /dev/disk/by-id/ -o cachefile=none "$pool" ||
  73         zpool reopen "$pool" ||
  74         zpool import -lfd /dev/disk/by-id/ -o cachefile=none "$pool" ||
  75         zpool clear -nFX "$pool"
  76         ${pkgs.systemd}/bin/systemctl restart zfs-mount.service
  77       '' + " %I";
  78     };
  79   };
  80 }