Complete rewrite: SnapRAID SMART logger with BackBlaze algorithm

Fetches SMART data from Scrutiny's InfluxDB and calculates failure
probabilities using the exact BackBlaze tables from SnapRAID source.

Key features:
- Calculates both v12 (with attr 193) and v13 (without attr 193) algorithms
- v12 matches SnapRAID pre-v13.0 (includes Load Cycle Count)
- v13 matches modern SnapRAID v13.0+ (excludes Load Cycle Count)
- Stores both values for trending and comparison
- Correctly applies bit masks (16-bit for 187/188, 32-bit for others)
- Annualizes monthly rates and applies Poisson distribution
- Logs to PostgreSQL with device metadata

Solved the mystery: SnapRAID v12 uses attribute 193 which was removed
in v13.0. Load cycle count has massive impact on failure predictions
for some drives (80% vs 4% difference).

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

debug_value_field.py

@@ -0,0 +1,79 @@
+#!/usr/bin/env python3
+"""
+Check the VALUE field (not raw_value) for SMART attributes
+"""
+
+import os
+from influxdb_client import InfluxDBClient
+from dotenv import load_dotenv
+
+load_dotenv()
+
+url = os.getenv('INFLUXDB_URL')
+token = os.getenv('INFLUXDB_TOKEN')
+org = os.getenv('INFLUXDB_ORG', 'scrutiny')
+bucket = os.getenv('INFLUXDB_BUCKET', 'metrics')
+
+client = InfluxDBClient(url=url, token=token, org=org)
+query_api = client.query_api()
+
+# Get VALUE field (normalized 0-100) for critical attributes
+query = f'''
+from(bucket: "{bucket}")
+    |> range(start: -1h)
+    |> filter(fn: (r) => r._measurement == "smart")
+    |> filter(fn: (r) => r.device_wwn == "0x5000c500c570663e")
+    |> filter(fn: (r) =>
+        r._field == "attr.5.value" or
+        r._field == "attr.187.value" or
+        r._field == "attr.188.value" or
+        r._field == "attr.197.value" or
+        r._field == "attr.198.value" or
+        r._field == "attr.5.raw_value" or
+        r._field == "attr.187.raw_value" or
+        r._field == "attr.188.raw_value" or
+        r._field == "attr.197.raw_value" or
+        r._field == "attr.198.raw_value"
+    )
+    |> last()
+'''
+
+print("=" * 80)
+print("/dev/sdc (ZLW0A3QJ) - should show 81% failure")
+print("Comparing InfluxDB values to smartctl output")
+print("=" * 80)
+
+result = query_api.query(query)
+
+attrs = {}
+for table in result:
+    for record in table.records:
+        field = record.get_field()
+        value = record.get_value()
+
+        parts = field.split('.')
+        if len(parts) >= 3:
+            attr_id = parts[1]
+            field_type = parts[2]
+
+            if attr_id not in attrs:
+                attrs[attr_id] = {}
+            attrs[attr_id][field_type] = value
+
+print("\nInfluxDB Data:")
+print("-" * 80)
+for attr_id in sorted(attrs.keys(), key=int):
+    print(f"\nAttribute {attr_id}:")
+    print(f"  value (normalized): {attrs[attr_id].get('value', 'N/A')}")
+    print(f"  raw_value: {attrs[attr_id].get('raw_value', 'N/A')}")
+
+print("\n" + "=" * 80)
+print("From smartctl -A /dev/sdc:")
+print("-" * 80)
+print("  5 Reallocated_Sector_Ct: VALUE=100, RAW_VALUE=0")
+print("187 Reported_Uncorrect:    VALUE=100, RAW_VALUE=0")
+print("188 Command_Timeout:       VALUE=100, RAW_VALUE=0")
+print("197 Current_Pending_Sector: VALUE=100, RAW_VALUE=0")
+print("198 Offline_Uncorrectable: VALUE=100, RAW_VALUE=0")
+
+client.close()