add hdparm to spin-down drives

hosts/yodaNas/configuration.nix

@@ -57,6 +57,7 @@ in
       #../../modules/ntfs.nix
       #../../modules/veracrypt.nix
       ../../modules/btrbk
+      ../../modules/spin-down.nix
     ];
 
   networking.hostName = "yodaNas";

hosts/yodaTab/configuration.nix

@@ -56,6 +56,7 @@ in
       ../../modules/ntfs.nix
       #../../modules/veracrypt.nix
       #../../modules/btrbk
+      #../../modules/spin-down.nix
     ];
 
   networking.hostName = "yodaTab";

hosts/yodaTux/configuration.nix

@@ -56,6 +56,7 @@ in
       ../../modules/ntfs.nix
       #../../modules/veracrypt.nix
       #../../modules/btrbk
+      #../../modules/spin-down.nix
     ];
 
   networking.hostName = "yodaTux";

hosts/yodaYoga/configuration.nix

@@ -57,6 +57,7 @@ in
       #../../modules/ntfs.nix
       #../../modules/veracrypt.nix
       #../../modules/btrbk
+      #../../modules/spin-down.nix
     ];
 
   networking.hostName = "yodaYoga";

modules/btrbk/default.nix

@@ -12,32 +12,6 @@
   # Print generated systemd unit file
   #   cat "$(systemctl show -P FragmentPath btrbk-<instance-name>.service)"
 
-  # TODO: Maybe the following is not necessary if using hd-idle anyways (!)
-  # TODO: Mount/Unmount backup drive
-  #   Example1:
-  #     - https://github.com/oxalica/nixos-config/blob/1b18628afda9cecca0bc8c348b91e3ae6ab56905/nixos/invar/btrbk.nix#L55
-  #     - https://github.com/oxalica/nixos-config/blob/1b18628afda9cecca0bc8c348b91e3ae6ab56905/nixos/invar/btrbk.nix#L64
-  #   Example2:
-  #     - https://github.com/emmanuelrosa/erosanix/blob/master/modules/btrbk.nix#L35-L42C7
-
-  # Spin down (unmounted/inactive) HDD disk.
-  # Inspired by https://www.reddit.com/r/NixOS/comments/751i5t/comment/do3f3l7/
-  #
-#  environment.systemPackages = with pkgs; [
-#    hd-idle
-#  ];
-#  systemd.services.hd-idle = {
-#    description = "Spin down inactive HDD";
-#    wantedBy = [ "multi-user.target" ];
-#    serviceConfig = {
-#      Type = "simple";
-#      # Options:
-#      # -a <disk>: Select disk for subsequent parameters.
-#      # -i 180: Spin down after 2 minutes (180 seconds) of inactivity.
-#      ExecStart = "${pkgs.hd-idle}/bin/hd-idle -a /dev/disk/by-id/XXX-XXX-XXX -i 180"; # TODO make disk id configurable
-#    };
-#  };
-
   services.btrbk = {
     extraPackages = [ pkgs.lz4 ];
     # Lowest scheduling priority.

modules/spin-down.nix

@@ -0,0 +1,84 @@
+{ config, pkgs, ... }:
+
+# hdparm - get/set SATA/IDE device parameters
+#   -q  Handle the next option quietly, suppressing normal output (but not error messages).
+#   -I  Print device information.
+#   -C  Check  the  current  IDE  power  mode status:
+#         unknown (drive does not support this command)
+#         active/idle (normal  operation)
+#         standby  (low  power mode, drive has spun down)
+#         sleeping (lowest power mode, drive is completely shut down)
+#   -S  Set the standby (spindown) timeout for the drive.
+#       The timeout specifies how long to wait in idle (with no disk activity) before turning off the motor to save power.
+#         The value of 0 disables spindown,
+#         the values from 1 to 240 specify multiples of 5 seconds
+#         and values from 241 to 251 specify multiples of 30 minutes.
+#   -y  Force an IDE drive to immediately enter the low power consumption standby mode, usually causing it to spin down.
+
+# Get power status:
+#   sudo hdparm -C /dev/disk/by-id/ata-WDC_WD40EFRX-68N32N0_WD-WCC7K0CPF0N1
+#   #=> drive state is: active/idle
+#
+# Spin down after 2 minutes (120s/5 = 24):
+#   sudo hdparm -S 24 /dev/disk/by-id/ata-WDC_WD40EFRX-68N32N0_WD-WCC7K0CPF0N1 # 4tb1
+#   sudo hdparm -S 24 /dev/disk/by-id/ata-WDC_WD30EFRX-68EUZN0_WD-WCC4N1173157 # 3tb1
+#   sudo hdparm -S 24 /dev/disk/by-id/ata-WDC_WD30EFRX-68EUZN0_WD-WMC4N0564095 # 3tb2
+#   #=> setting standby to 24 (2 minutes)
+#
+# ... after >> 2 minutes ...
+#
+# Query disk without waking it up:
+#   https://wiki.archlinux.org/title/hdparm#Querying_the_status_of_the_disk_without_waking_it_up
+#   sudo smartctl -i -n standby /dev/disk/by-id/ata-WDC_WD40EFRX-68N32N0_WD-WCC7K0CPF0N1
+#   #=> Device is in STANDBY mode, exit(2)
+#
+# Get power status:
+#   sudo hdparm -C /dev/disk/by-id/ata-WDC_WD40EFRX-68N32N0_WD-WCC7K0CPF0N1
+#   sudo hdparm -C /dev/disk/by-id/ata-WDC_WD30EFRX-68EUZN0_WD-WCC4N1173157
+#   sudo hdparm -C /dev/disk/by-id/ata-WDC_WD30EFRX-68EUZN0_WD-WMC4N0564095
+#   #=> drive state is: standby
+
+# Power savings.
+#   With 12tb1, 3tb1, 3tb2 spinning and 4tb1 spun-down: 26.1 W
+#   With 12tb1 spinning and 3tb1, 3tb2, 4tb1 spun-down: 19.8 W
+#   -> WD30EFRX measured idle spinning vs standby = +3.15 W
+#   -> WD30EFRX advertised idle spinning vs unplugged = +3.0 W
+
+# See also: Systemd service to spin down after boot. https://wiki.archlinux.org/title/hdparm#Putting_a_drive_to_sleep_directly_after_boot
+
+# TODO: For external (USB-)disks, use `hd-idle`.
+# https://www.reddit.com/r/NixOS/comments/751i5t/comment/do3f3l7/
+#   # Options:
+#   # -a <disk>: Select disk for subsequent parameters.
+#   # -i 180: Spin down after 2 minutes (180 seconds) of inactivity.
+#   ExecStart = "${pkgs.hd-idle}/bin/hd-idle -a /dev/disk/by-id/XXX-XXX-XXX -i 180";
+
+{
+  environment.systemPackages = with pkgs; [
+    hdparm
+  ];
+  systemd.services."hdparm-4tb1" = {
+    description = "Spin down inactive HDD";
+    wantedBy = [ "multi-user.target" ];
+    serviceConfig = {
+      Type = "oneshot";
+      ExecStart = "${pkgs.hdparm}/bin/hdparm -S 24 /dev/disk/by-id/ata-WDC_WD40EFRX-68N32N0_WD-WCC7K0CPF0N1";
+    };
+  };
+  systemd.services."hdparm-3tb1" = {
+    description = "Spin down inactive HDD";
+    wantedBy = [ "multi-user.target" ];
+    serviceConfig = {
+      Type = "oneshot";
+      ExecStart = "${pkgs.hdparm}/bin/hdparm -S 24 /dev/disk/by-id/ata-WDC_WD30EFRX-68EUZN0_WD-WCC4N1173157";
+    };
+  };
+  systemd.services."hdparm-3tb2" = {
+    description = "Spin down inactive HDD";
+    wantedBy = [ "multi-user.target" ];
+    serviceConfig = {
+      Type = "oneshot";
+      ExecStart = "${pkgs.hdparm}/bin/hdparm -S 24 /dev/disk/by-id/ata-WDC_WD30EFRX-68EUZN0_WD-WMC4N0564095";
+    };
+  };
+}