feat: add smart alerting and noatime to disks

hosts/web-arm/modules/grafana/alerting/storage/raid_alerts.nix

@@ -0,0 +1,102 @@
+{ lib, pkgs, config, ... }:
+{
+  grafanaAlertRuleDefinitions = [
+    # RAID array degraded - critical
+    {
+      uid = "raid-array-degraded-uid";
+      title = "RaidArrayDegraded";
+      condition = "D";
+      data = [
+        {
+          refId = "A";
+          datasourceUid = "vm-datasource-uid";
+          relativeTimeRange = { from = 300; to = 0; };
+          model = {
+            expr = ''mdadm_array_state == 0'';
+            instant = false;
+          };
+        }
+        {
+          refId = "C";
+          datasourceUid = "__expr__";
+          model = {
+            type = "reduce";
+            expression = "A";
+            reducer = "last";
+          };
+        }
+        {
+          refId = "D";
+          datasourceUid = "__expr__";
+          model = {
+            type = "math";
+            expression = "$C == 0";
+          };
+        }
+      ];
+      for = "0s";
+      noDataState = "NoData";
+      execErrState = "Error";
+      annotations = {
+        summary = "RAID array {{ $labels.array }} is degraded";
+        description = ''
+          RAID array {{ $labels.array }} on {{ $labels.instance }} is in state "{{ $labels.state }}".
+          The array is not in a healthy state. Check for failed disks immediately!
+        '';
+      };
+      labels = {
+        severity = "critical";
+        category = "storage";
+      };
+    }
+
+    # RAID missing devices - critical
+    {
+      uid = "raid-missing-devices-uid";
+      title = "RaidMissingDevices";
+      condition = "D";
+      data = [
+        {
+          refId = "A";
+          datasourceUid = "vm-datasource-uid";
+          relativeTimeRange = { from = 300; to = 0; };
+          model = {
+            expr = ''mdadm_array_devices_active < mdadm_array_devices_total'';
+            instant = false;
+          };
+        }
+        {
+          refId = "C";
+          datasourceUid = "__expr__";
+          model = {
+            type = "reduce";
+            expression = "A";
+            reducer = "last";
+          };
+        }
+        {
+          refId = "D";
+          datasourceUid = "__expr__";
+          model = {
+            type = "math";
+            expression = "$C > 0";
+          };
+        }
+      ];
+      for = "0s";
+      noDataState = "NoData";
+      execErrState = "Error";
+      annotations = {
+        summary = "RAID array {{ $labels.array }} has missing devices";
+        description = ''
+          RAID array {{ $labels.array }} on {{ $labels.instance }} has fewer active devices than expected.
+          A disk may have failed or been removed. Check array status immediately!
+        '';
+      };
+      labels = {
+        severity = "critical";
+        category = "storage";
+      };
+    }
+  ];
+}