fan_speed/monitor.sh

#!/bin/bash
#
# Disk temperature monitoring, trend tracking and email alarms.
#
# Sourced by fan_speed.sh alongside functions.sh. functions.sh is vendored from
# upstream (tigerblue77/Dell_iDRAC_fan_controller_Docker); everything in here is
# local, so keep the two files separate to keep that boundary readable.

# ---------------------------------------------------------------- configuration

# Internal drives only. The DAS shelf enumerates behind a SAS expander
# (*-sas-exp*) and has its own controller - it must not drive server fans.
DISK_GLOB=${DISK_GLOB:-/dev/disk/by-path/pci-*-scsi-*}

# Each drive's fan ramp is derived from its own maximum operating temperature:
#   ramp starts at  limit - DISK_RAMP_LOW_OFFSET
#   full speed at   limit - DISK_RAMP_HIGH_OFFSET
# Larger low offset = react earlier = louder. See README before changing.
DISK_RAMP_LOW_OFFSET=${DISK_RAMP_LOW_OFFSET:-18}
DISK_RAMP_HIGH_OFFSET=${DISK_RAMP_HIGH_OFFSET:-8}

# A drive this close to its own limit raises an alarm - the fans are already
# flat out for it and it is still climbing.
DISK_ALARM_OFFSET=${DISK_ALARM_OFFSET:-5}

# Drives report their limit but do not agree on what it means: Samsung and
# Kioxia report a true operating maximum (70), Toshiba and Seagate report 60,
# WD Reds report 85 - the SCT critical limit, not an operating maximum.
# Clamp by class so one optimistic drive cannot quietly disable cooling.
HDD_LIMIT_CAP=${HDD_LIMIT_CAP:-60}
SSD_LIMIT_CAP=${SSD_LIMIT_CAP:-70}

ALERT_EMAIL=${ALERT_EMAIL:-Servers@ntfy1.izebra.xyz}
ALERT_COOLDOWN=${ALERT_COOLDOWN:-3600}
STATE_DIR=${STATE_DIR:-/root/fan_speed/state}
LOG_FILE=${LOG_FILE:-/root/fan_speed/log/fan_speed.log}

TREND_FILE=${TREND_FILE:-/root/fan_speed/log/temps.csv}
TREND_SAMPLES=${TREND_SAMPLES:-90}       # 90 x 10s CHECK_INTERVAL = 15 minutes
TREND_RISE_ALARM=${TREND_RISE_ALARM:-8}  # degrees of climb across that window

SMART_CHECK_INTERVAL=${SMART_CHECK_INTERVAL:-3600}

# ------------------------------------------------------------------ disk temps

log_line() {
  echo "$(date +'%Y-%m-%d %H:%M:%S') || $*" >> "$LOG_FILE"
}

# Block devices behind DISK_GLOB, deduplicated. Resolved fresh every call:
# kernel names are not stable, a shelf rescan renamed sdaa-sdai to sds-sdaa.
disk_devices() {
  local link dev
  for link in $DISK_GLOB; do
    case "$link" in *-part*) continue ;; esac
    [ -e "$link" ] || continue
    dev=$(readlink -f "$link")
    [ -b "$dev" ] && echo "$dev"
  done | sort -u
}

# smartctl -A output on stdin -> temperature in celsius, empty if it did not say.
# Drives disagree on the attribute name: 194 Temperature_Celsius (most),
# 190 Airflow_Temperature_Cel (Seagate), 194 Temperature_Internal (Intel),
# and SCSI/SAS drives report a "Current Drive Temperature" line instead.
# Temperature_Difference_from_100 is a delta, not a reading - never match it.
parse_disk_temperature() {
  awk '
    /Current Drive Temperature/           { print $4; exit }
    /^ *[0-9]+ +[A-Za-z_]*Temperature[A-Za-z_]*/ && !/Difference/ { print $10; exit }'
}

# smartctl -x output on stdin -> the drive's own maximum operating temperature.
parse_disk_limit() {
  awk '
    /Min\/Max Temperature Limit/ { split($0, a, /[ \/]+/); for (i in a) if (a[i] ~ /^[0-9]+$/) v = a[i]; print v; exit }
    /Drive Trip Temperature/     { print $4; exit }'
}

# -n standby: skip a sleeping drive rather than spinning it up to measure it.
disk_temperature() {
  smartctl -n standby -A "$1" 2>/dev/null | parse_disk_temperature
}

# The drive's own limit, clamped by class (see HDD_LIMIT_CAP above).
disk_limit() {
  local dev=$1 limit rotational cap
  limit=$(smartctl -x "$dev" 2>/dev/null | parse_disk_limit)
  rotational=$(cat "/sys/block/$(basename "$dev")/queue/rotational" 2>/dev/null)
  if [ "$rotational" = 1 ]; then cap=$HDD_LIMIT_CAP; else cap=$SSD_LIMIT_CAP; fi
  if [ -z "$limit" ] || ! [ "$limit" -le "$cap" ] 2>/dev/null; then limit=$cap; fi
  echo "$limit"
}

# Limits do not change, and smartctl -x is far heavier than -A. Read them once.
declare -A DISK_LIMIT
cache_disk_limits() {
  local dev
  DISK_LIMIT=()
  for dev in $(disk_devices); do
    DISK_LIMIT[$dev]=$(disk_limit "$dev")
  done
  DISK_COUNT_EXPECTED=${#DISK_LIMIT[@]}
}

# Reads every drive. Sets:
#   HOTTEST_DISK_TEMPERATURE / _DEVICE / _LIMIT, DISK_FAN_SPEED, DISKS_READ
# Each drive is interpolated against its OWN limit and the highest resulting fan
# speed wins - so a 50c SSD rated to 70 asks for less than a 45c disk rated to 60.
# That makes the curve independent of drive technology and of bay position.
retrieve_disk_temperatures() {
  local dev temp limit speed
  HOTTEST_DISK_TEMPERATURE=0
  HOTTEST_DISK_DEVICE="-"
  HOTTEST_DISK_LIMIT=0
  DISK_FAN_SPEED=$LOW_FAN_SPEED
  DISKS_READ=0

  for dev in $(disk_devices); do
    temp=$(disk_temperature "$dev")
    [ -n "$temp" ] || continue
    DISKS_READ=$((DISKS_READ + 1))

    limit=${DISK_LIMIT[$dev]}
    [ -n "$limit" ] || limit=$(disk_limit "$dev")

    speed=$(calculate_interpolated_fan_speed "$temp" \
              $((limit - DISK_RAMP_LOW_OFFSET)) $((limit - DISK_RAMP_HIGH_OFFSET)) \
              "$LOW_FAN_SPEED" "$HIGH_FAN_SPEED")
    [ "$speed" -gt "$DISK_FAN_SPEED" ] && DISK_FAN_SPEED=$speed

    if [ "$temp" -gt "$HOTTEST_DISK_TEMPERATURE" ]; then
      HOTTEST_DISK_TEMPERATURE=$temp
      HOTTEST_DISK_DEVICE=$dev
      HOTTEST_DISK_LIMIT=$limit
    fi
  done
}

# --------------------------------------------------------------------- alarms

notify() {
  local subject=$1 body=$2
  if [ -n "$DRY_RUN" ]; then
    echo "MAIL[$ALERT_EMAIL] $subject"
  else
    printf '%s\n' "$body" | mail -s "$subject" "$ALERT_EMAIL"
  fi
  log_line "ALERT $subject"
}

# raise_alert <key> <subject> <body>
# Rate limited per key. Without this a 10s loop sends 360 mails an hour and the
# alarm becomes the outage.
raise_alert() {
  local key=$1 subject=$2 body=$3
  local stamp="$STATE_DIR/$key.alert" now last
  mkdir -p "$STATE_DIR"
  now=$(date +%s)
  if [ -f "$stamp" ]; then
    last=$(cat "$stamp")
    [ $((now - last)) -lt "$ALERT_COOLDOWN" ] && return 0
  fi
  echo "$now" > "$stamp"
  notify "$subject" "$body"
}

# clear_alert <key> <subject> - one recovery notice, only if the alarm was up.
clear_alert() {
  local key=$1 subject=$2
  local stamp="$STATE_DIR/$key.alert"
  [ -f "$stamp" ] || return 0
  rm -f "$stamp"
  notify "$subject" "Recovered at $(date '+%Y-%m-%d %H:%M:%S')."
}

# ---------------------------------------------------------------------- trend

# record_sample <cpu> <gpu> <disk> <fan>
record_sample() {
  mkdir -p "$(dirname "$TREND_FILE")"
  echo "$(date +%s),$1,$2,$3,$4" >> "$TREND_FILE"
  if [ "$(wc -l < "$TREND_FILE")" -gt $((TREND_SAMPLES * 2)) ]; then
    tail -n "$TREND_SAMPLES" "$TREND_FILE" > "$TREND_FILE.tmp" && mv "$TREND_FILE.tmp" "$TREND_FILE"
  fi
}

# rise_over_window <column> -> degrees climbed from the oldest sample in the
# window to the newest. 0 until there is a full window of history, so a restart
# cannot alarm on a partial series.
# Columns: 2 cpu, 3 gpu, 4 disk, 5 fan.
rise_over_window() {
  local column=$1 oldest newest lines
  lines=$(wc -l < "$TREND_FILE" 2>/dev/null || echo 0)
  if [ "$lines" -lt "$TREND_SAMPLES" ]; then echo 0; return; fi
  oldest=$(tail -n "$TREND_SAMPLES" "$TREND_FILE" | head -1 | cut -d, -f"$column")
  newest=$(tail -n 1 "$TREND_FILE" | cut -d, -f"$column")
  [ -n "$oldest" ] && [ -n "$newest" ] || { echo 0; return; }
  echo $((newest - oldest))
}

# --------------------------------------------------------------- SMART health

# Expensive across two dozen drives - the caller runs this hourly, not per loop.
check_disk_health() {
  local dev status failed=""
  for dev in $(disk_devices); do
    status=$(smartctl -H "$dev" 2>/dev/null | grep -iE "overall-health|SMART Health Status")
    [ -n "$status" ] || continue
    case "$status" in
      *PASSED*|*OK*) ;;
      *) failed+="$dev: $status"$'\n' ;;
    esac
  done
  if [ -n "$failed" ]; then
    raise_alert smart "SMART failure on $(hostname)" "$failed"
  else
    clear_alert smart "SMART recovered on $(hostname)"
  fi
}