diff --git a/modules/hardware.nix b/modules/hardware.nix
index e2cdbf6..f0ba280 100644
--- a/modules/hardware.nix
+++ b/modules/hardware.nix
@@ -23,13 +23,48 @@
   hardware.enableRedistributableFirmware = true;
 
   # HDD I/O tuning for torrent seeding workload (high-concurrency random reads).
+  #
   # mq-deadline sorts requests into elevator sweeps, reducing seek distance.
   # Aggressive deadlines (15s) let the scheduler accumulate more ops before dispatching,
   # maximizing coalescence — latency is irrelevant since torrent peers tolerate 30-60s.
   # fifo_batch=128 keeps sweeps long; writes_starved=16 heavily favors reads.
   # 4 MiB readahead matches libtorrent piece extent affinity for sequential prefetch.
-  services.udev.extraRules = ''
-    ACTION=="add|change", KERNEL=="sd[a-z]", ATTR{queue/rotational}=="1", ATTR{queue/scheduler}="mq-deadline", ATTR{queue/read_ahead_kb}="4096", ATTR{queue/nr_requests}="512"
-    ACTION=="add|change", KERNEL=="sd[a-z]", ATTR{queue/rotational}=="1", ENV{ID_ATA_ROTATION_RATE_RPM}!="0", RUN+="${pkgs.bash}/bin/bash -c 'echo 15000 > /sys$devpath/queue/iosched/read_expire; echo 15000 > /sys$devpath/queue/iosched/write_expire; echo 128 > /sys$devpath/queue/iosched/fifo_batch; echo 16 > /sys$devpath/queue/iosched/writes_starved; echo 4096 > /sys$devpath/queue/max_sectors_kb 2>/dev/null || true'"
-  '';
+  #
+  # This runs as a systemd oneshot rather than udev rules because the NixOS ZFS module
+  # hardcodes a udev rule that forces scheduler="none" on all ZFS member partitions'
+  # parent disks, overriding any scheduler set via udev on the disk event.
+  systemd.services.hdd-io-tuning = {
+    description = "HDD I/O scheduler and queue tuning";
+    after = [
+      "zfs-import.target"
+      "systemd-udev-settle.service"
+    ];
+    wantedBy = [ "multi-user.target" ];
+    serviceConfig = {
+      Type = "oneshot";
+      RemainAfterExit = true;
+    };
+    script = ''
+      for dev in /sys/block/sd*; do
+        [ -f "$dev/queue/rotational" ] || continue
+        [ "$(cat "$dev/queue/rotational")" = "1" ] || continue
+
+        # skip removable devices (USB sticks report removable=1)
+        [ "$(cat "$dev/removable")" = "0" ] || continue
+
+        echo mq-deadline > "$dev/queue/scheduler"
+        echo 4096 > "$dev/queue/read_ahead_kb"
+        echo 512 > "$dev/queue/nr_requests"
+
+        echo 15000 > "$dev/queue/iosched/read_expire"
+        echo 15000 > "$dev/queue/iosched/write_expire"
+        echo 128 > "$dev/queue/iosched/fifo_batch"
+        echo 16 > "$dev/queue/iosched/writes_starved"
+
+        echo 4096 > "$dev/queue/max_sectors_kb" 2>/dev/null || true
+
+        echo "Tuned $(basename "$dev"): mq-deadline, 4M readahead, 15s deadlines"
+      done
+    '';
+  };
 }