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Varaverk/Monitors/zfs_memory_snapshot.sh
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#!/bin/bash
# ==============================================================================================
# ============================= ZFS Memory Snapshot ============================================
# ==============================================================================================
#
# PURPOSE
# ─────────────────────────────────────────────────────────────────────────────
# Weekly ZFS pool health and memory diagnostic report. Scheduled Sunday 6am —
# first in the Sunday monitoring block, before other scripts run. Informational
# only — system_watchdog.sh handles threshold-based intervention.
#
# Combines ZFS pool status, ARC statistics, Docker memory usage, and kernel
# memory pressure into a single snapshot. In normal mode output goes to both
# console (for User Scripts output log) and ZFS_REPORT_LOG for week-over-week
# comparison. In --dry-run mode, console only — nothing written to the log.
#
# ==============================================================================================
# OPERATIONAL MODEL
# ==============================================================================================
#
# Five report sections (each skips gracefully if its data source is unavailable):
#
# ZFS pool health — status, state, errors per pool. Pools in
# ZFS_REPORT_IGNORE_POOLS excluded from the report
# (still fully monitored by unRAID — report-only exclusion).
# ARC statistics — current ARC vs max, metadata pressure, hit rate.
# Warns if ARC utilisation exceeds ZFS_REPORT_ARC_WARN_PCT, or if
# ARC headroom (max - current) drops below ZFS_REPORT_ARC_FREE_WARN_GB.
# Memory status — total, free, available RAM (informational only — see note below).
# Warns if available < ZFS_REPORT_AVAIL_WARN_GB.
# Docker memory — top ZFS_REPORT_DOCKER_TOP containers by memory usage.
# Useful for spotting containers approaching watchdog limits.
# Kernel pressure — vmstat snapshot (3 samples).
#
# ==============================================================================================
# DESIGN PRINCIPLES
# ==============================================================================================
#
# Informational, Not Interventional
# This script reports — it does not act. system_watchdog.sh handles
# threshold-based intervention. Keeping the roles separate means the report
# is never suppressed by the same logic that triggers remediation.
#
# Week-Over-Week Comparison
# Output is written to ZFS_REPORT_LOG so the same snapshot can be reviewed
# across weeks. Memory pressure and ARC creep are slow — a single run is
# rarely conclusive; the trend across weeks is what matters.
#
# Section Independence
# Each of the five report sections guards its own data source. ZFS not
# available, Docker not responding — those sections skip, the rest still run.
# A partial report is more useful than no report.
#
# ARC Headroom, Not System Free RAM
# ZFS ARC deliberately grows to use most of the RAM the system isn't otherwise
# using — that's the point of a page cache. System-wide "free" RAM being low is
# therefore normal and not a signal of anything, so the memory warning is based
# on ARC headroom (ARC_MAX - ARC_CURRENT) instead — how much room ARC itself has
# left before it hits its configured ceiling. "Available" RAM (which accounts for
# reclaimable cache) is still checked separately as a true system-pressure signal.
#
# ==============================================================================================
# OPERATIONAL SAFEGUARDS
# ==============================================================================================
#
# Single Instance Lock
# acquire_lock prevents duplicate runs — zpool and docker stats are slow.
#
# Per-Host Pool Ignore List
# detect_hosts() aliases HOST*_ZFS_REPORT_IGNORE_POOLS → ZFS_REPORT_IGNORE_POOLS.
# Single-disk JBOD members excluded from report noise per server.
#
# ZFS Availability Guard
# Skips pool and ARC sections gracefully if ZFS is not available on this server.
#
# Docker Availability Guard
# Skips container memory section gracefully if Docker is not responding.
#
# Docker Stats Timeout
# DOCKER_TIMEOUT caps docker stats calls. A hung daemon does not block the report.
#
# ==============================================================================================
# STATE FILES
# ==============================================================================================
#
# ZFS_REPORT_LOG — /var/log/zfs-weekly-health.log (tmpfs, resets on reboot)
# Weekly report written here for comparison across runs. Open the log to
# see pool health trend week over week without remembering last week's values.
# In dry-run mode, console only — nothing written.
#
# ==============================================================================================
# CONFIGURATION
# ==============================================================================================
#
# host*.conf
#
# HOST*_ZFS_REPORT_IGNORE_POOLS
# Pools excluded from health reporting. Single-disk JBOD members generate
# expected high-usage warnings — exclude them to reduce report noise.
# Aliased by detect_hosts() → ZFS_REPORT_IGNORE_POOLS.
#
# master.conf
#
# ZFS_REPORT_LOG
# Log file path for weekly reports. (default: /var/log/zfs-weekly-health.log)
#
# ZFS_REPORT_ARC_WARN_PCT
# Warn if ARC is using more than this percentage of its configured max. (default: 90)
#
# ZFS_REPORT_ARC_FREE_WARN_GB
# Warn if ARC headroom (ARC_MAX - ARC_CURRENT) drops below this many GB. (default: 10)
#
# ZFS_REPORT_AVAIL_WARN_GB
# Warn if available RAM is below this threshold in GB. (default: 20)
#
# ZFS_REPORT_DOCKER_TOP
# Number of top Docker containers by memory usage to include. (default: 10)
#
# ==============================================================================================
# RUNTIME MODES
# ==============================================================================================
#
# zfs_memory_snapshot.sh
# Generate report, write to ZFS_REPORT_LOG and console. Notify on warnings.
#
# zfs_memory_snapshot.sh --dry-run
# Generate report to console only. No log write, no notifications.
#
# zfs_memory_snapshot.sh --status
# Show pool ignore list and threshold configuration. Then exit.
#
# zfs_memory_snapshot.sh --log
# Verbose output during report generation.
#
# ==============================================================================================
SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
source "$SCRIPT_DIR/../load_config.sh"
parse_args "$@"
DOCKER_TIMEOUT=15
# ==============================================================================================
# ━━━ Setup ━━━
# ==============================================================================================
if [[ "$EUID" -ne 0 ]]; then
error "Must be run as root"
exit 1
fi
acquire_lock
# detect_hosts() sets MY_ID and aliases HOST*_ZFS_REPORT_IGNORE_POOLS
detect_hosts
# Build ignore pool lookup map — O(1) check per pool
declare -A IGNORE_POOL_MAP
for pool in "${ZFS_REPORT_IGNORE_POOLS[@]}"; do
[[ -n "$pool" ]] && IGNORE_POOL_MAP["$pool"]=1
done
log "Identity: $MY_ID ($LOCAL_SERVER_NAME)"
log "Ignoring pools: ${ZFS_REPORT_IGNORE_POOLS[*]:-none}"
log "$ICON_GEAR Config: arc-warn=${ZFS_REPORT_ARC_WARN_PCT}% arc-free-warn=${ZFS_REPORT_ARC_FREE_WARN_GB}GB avail-warn=${ZFS_REPORT_AVAIL_WARN_GB}GB docker-top=${ZFS_REPORT_DOCKER_TOP}"
# Tee output to log file unless dry run
if [[ "$DRY_RUN" == false ]]; then
mkdir -p "$(dirname "$ZFS_REPORT_LOG")"
exec > >(tee -a "$ZFS_REPORT_LOG") 2>&1
fi
[[ "$DRY_RUN" == true ]] && warn "DRY RUN — output will not be written to log"
# ==============================================================================================
# ━━━ Status ━━━
# ==============================================================================================
if [[ "$SHOW_STATUS" == true ]]; then
echo ""
echo "━━━━━ $ICON_SUMMARY STATUS ━━━━━"
echo "$ICON_HOST Identity: $MY_ID ($LOCAL_SERVER_NAME)"
echo "$ICON_ZFS Log file: $ZFS_REPORT_LOG"
echo "$ICON_ZFS ARC warn: ${ZFS_REPORT_ARC_WARN_PCT}%"
echo "$ICON_ZFS ARC free warn: ${ZFS_REPORT_ARC_FREE_WARN_GB}GB"
echo "$ICON_MEM Avail warn: ${ZFS_REPORT_AVAIL_WARN_GB}GB"
echo "$ICON_CONTAINERS Docker top: $ZFS_REPORT_DOCKER_TOP"
echo "$ICON_ZFS Ignore pools: ${ZFS_REPORT_IGNORE_POOLS[*]:-none}"
echo "$ICON_GEAR Dry Run: $DRY_RUN"
echo "━━━━━━━━━━━━━━━━━━━━━━━"
exit 0
fi
# ==============================================================================================
# ━━━ Report ━━━
# ==============================================================================================
WARNINGS=()
START=$(date +%s)
DATE=$(date '+%Y-%m-%d %H:%M:%S')
echo ""
echo "━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━"
echo " $ICON_ZFS ZFS WEEKLY HEALTH REPORT — $DATE"
echo " $ICON_HOST $MY_ID$LOCAL_SERVER_NAME"
echo "━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━"
# ── ZFS Pool Health ───────────────────────────────────────────────────────────────────────────
echo ""
echo "━━━ $ICON_ZFS ZFS Pool Health ━━━"
if ! command -v zpool >/dev/null 2>&1; then
warn "ZFS not available on this system — skipping pool checks"
else
# Pool status — filtered to key lines, ignoring specified pools
CURRENT_POOL=""
while IFS= read -r line; do
if [[ "$line" =~ ^[[:space:]]*pool:[[:space:]]*(.+) ]]; then
CURRENT_POOL="${BASH_REMATCH[1]// /}"
fi
[[ -n "${IGNORE_POOL_MAP[$CURRENT_POOL]:-}" ]] && continue
echo " $line"
done < <(zpool status 2>/dev/null | grep -E "pool:|state:|status:|errors:|scan:")
echo ""
# Pool list — filter out ignored pools
zpool list 2>/dev/null | while IFS= read -r line; do
if [[ "$line" == NAME* ]]; then
echo " $line"
continue
fi
pool_name=$(echo "$line" | awk '{print $1}')
[[ -n "${IGNORE_POOL_MAP[$pool_name]:-}" ]] && continue
echo " $line"
done
# Check for unhealthy non-ignored pools
UNHEALTHY=$(zpool list -H -o name,health 2>/dev/null | \
while IFS=$'\t' read -r name health; do
[[ -n "${IGNORE_POOL_MAP[$name]:-}" ]] && continue
[[ "$health" != "ONLINE" ]] && echo "$name: $health"
done)
if [[ -n "$UNHEALTHY" ]]; then
error "One or more ZFS pools are NOT ONLINE: $UNHEALTHY"
WARNINGS+=("ZFS pool unhealthy: $UNHEALTHY")
else
echo "All monitored ZFS pools are ONLINE ✅"
fi
if [[ ${#ZFS_REPORT_IGNORE_POOLS[@]} -gt 0 ]]; then
log "Ignored pools: ${ZFS_REPORT_IGNORE_POOLS[*]}"
fi
fi
# ── ARC Statistics ────────────────────────────────────────────────────────────────────────────
echo ""
echo "━━━ $ICON_ZFS ARC Statistics ━━━"
if [[ ! -f /proc/spl/kstat/zfs/arcstats ]]; then
warn "ZFS arcstats not available — skipping ARC section"
else
# zfs_arc_max reads 0 when it has been left at the default, which is a value rather than a
# failure — so the || fallback never fires for the case that actually needs it, exactly like a
# grep -c that prints 0 and exits 1. Zero here would reach the ARC_PCT division below, and awk
# treats division by zero as fatal: it prints nothing, ARC_PCT comes back empty, and the whole
# ARC section reports blanks. c_max is the cap the kernel is really enforcing either way.
ARC_MAX=$(cat /sys/module/zfs/parameters/zfs_arc_max 2>/dev/null || echo 0)
ARC_MAX="${ARC_MAX//[^0-9]/}"
if [[ "${ARC_MAX:-0}" -eq 0 ]]; then
ARC_MAX=$(awk '/^c_max / {print $3}' /proc/spl/kstat/zfs/arcstats 2>/dev/null)
ARC_MAX="${ARC_MAX:-0}"
fi
ARC_SIZE=$(awk '/^size / {print $3}' /proc/spl/kstat/zfs/arcstats)
ARC_META_USED=$(awk '/^arc_meta_used / {print $3}' /proc/spl/kstat/zfs/arcstats)
ARC_MAX_GB=$(bytes_to_gb "$ARC_MAX" 1)
ARC_CUR_GB=$(bytes_to_gb "$ARC_SIZE" 1)
ARC_META_GB=$(bytes_to_gb "$ARC_META_USED" 1)
ARC_PCT=$(awk "BEGIN {printf \"%.1f\", $ARC_SIZE * 100 / $ARC_MAX}")
ARC_PCT_INT=$(printf "%.0f" "$ARC_PCT")
ARC_FREE_GB=$(awk "BEGIN {printf \"%d\", ($ARC_MAX - $ARC_SIZE) / 1073741824}")
echo " $ICON_ZFS ARC Max: ${ARC_MAX_GB}GB"
echo " $ICON_ZFS ARC Current: ${ARC_CUR_GB}GB"
echo " $ICON_ZFS ARC Meta Used: ${ARC_META_GB}GB"
echo " $ICON_ZFS ARC Utilization: ${ARC_PCT}%"
echo " $ICON_ZFS ARC Free: ${ARC_FREE_GB}GB"
if [[ "$ARC_PCT_INT" -ge "$ZFS_REPORT_ARC_WARN_PCT" ]]; then
warn "ARC utilization ${ARC_PCT}% — above ${ZFS_REPORT_ARC_WARN_PCT}% threshold"
WARNINGS+=("ARC high: ${ARC_PCT}%")
else
log "ARC utilization ${ARC_PCT}% — within threshold ✅"
fi
if [[ "$ARC_FREE_GB" -lt "$ZFS_REPORT_ARC_FREE_WARN_GB" ]]; then
warn "ARC free ${ARC_FREE_GB}GB — below ${ZFS_REPORT_ARC_FREE_WARN_GB}GB threshold"
WARNINGS+=("ARC headroom low: ${ARC_FREE_GB}GB")
else
log "ARC free ${ARC_FREE_GB}GB — within threshold ✅"
fi
echo ""
META_MRU_GHOST=$(awk '/^mru_ghost_metadata / {print $3}' \
/proc/spl/kstat/zfs/arcstats 2>/dev/null || echo 0)
META_MFU_GHOST=$(awk '/^mfu_ghost_metadata / {print $3}' \
/proc/spl/kstat/zfs/arcstats 2>/dev/null || echo 0)
META_MISSES=$(awk '/^demand_metadata_misses / {print $3}' \
/proc/spl/kstat/zfs/arcstats 2>/dev/null || echo 0)
MRU_GB=$(bytes_to_gb "$META_MRU_GHOST")
MFU_GB=$(bytes_to_gb "$META_MFU_GHOST")
echo " $ICON_ZFS MRU Ghost: ${MRU_GB}GB"
echo " $ICON_ZFS MFU Ghost: ${MFU_GB}GB"
echo " $ICON_ZFS Metadata Misses: ${META_MISSES}"
fi
# ── Memory Status ─────────────────────────────────────────────────────────────────────────────
echo ""
echo "━━━ $ICON_MEM Memory Status ━━━"
FREE_HUMAN=$(free -h | awk '/Mem:/ {print $4}')
AVAIL_HUMAN=$(free -h | awk '/Mem:/ {print $7}')
TOTAL_HUMAN=$(free -h | awk '/Mem:/ {print $2}')
AVAIL_GB=$(free -g | awk '/Mem:/ {print $7}')
echo " $ICON_MEM Total RAM: $TOTAL_HUMAN"
echo " $ICON_MEM Free RAM: $FREE_HUMAN (informational — ARC intentionally uses most of this)"
echo " $ICON_MEM Available RAM: $AVAIL_HUMAN"
if [[ "$AVAIL_GB" -lt "$ZFS_REPORT_AVAIL_WARN_GB" ]]; then
warn "Available RAM ${AVAIL_HUMAN} — below ${ZFS_REPORT_AVAIL_WARN_GB}GB threshold"
WARNINGS+=("Low available RAM: ${AVAIL_HUMAN}")
else
log "Available RAM ${AVAIL_HUMAN} — within threshold ✅"
fi
# ── Docker Memory ─────────────────────────────────────────────────────────────────────────────
echo ""
echo "━━━ $ICON_CONTAINERS Top $ZFS_REPORT_DOCKER_TOP Docker Memory Users ━━━"
if ! command -v docker >/dev/null 2>&1; then
warn "Docker not available — skipping container memory section"
else
timeout "$DOCKER_TIMEOUT" docker stats --no-stream \
--format "table {{.Name}}\t{{.MemUsage}}\t{{.MemPerc}}" \
2>/dev/null | head -n $(( ZFS_REPORT_DOCKER_TOP + 1 )) | \
while IFS= read -r line; do
echo " $line"
done
fi
# ── Kernel Pressure ───────────────────────────────────────────────────────────────────────────
echo ""
echo "━━━ $ICON_GEAR Kernel Pressure ━━━"
if ! command -v vmstat >/dev/null 2>&1; then
warn "vmstat not available — skipping kernel pressure section"
else
vmstat 1 3 2>/dev/null | while IFS= read -r line; do
echo " $line"
done
fi
END=$(date +%s)
# ── Summary ───────────────────────────────────────────────────────────────────────────────────
echo ""
echo "━━━━━ $ICON_SUMMARY ZFS REPORT SUMMARY ━━━━━"
echo "$ICON_HOST Identity: $MY_ID ($LOCAL_SERVER_NAME)"
echo "$ICON_TIME Duration: $(format_duration $(( END - START )))"
echo "$ICON_ZFS Log: $ZFS_REPORT_LOG"
[[ ${#ZFS_REPORT_IGNORE_POOLS[@]} -gt 0 ]] && \
log "Ignored: ${ZFS_REPORT_IGNORE_POOLS[*]}"
echo ""
if [[ ${#WARNINGS[@]} -eq 0 ]]; then
echo "$ICON_DONE All checks within thresholds ✅"
else
echo "$ICON_WARN Warnings: ${#WARNINGS[@]}"
for w in "${WARNINGS[@]}"; do
echo " $ICON_WARN $w"
done
notify "ZFS weekly report on $(hostname)${#WARNINGS[@]} warning(s): ${WARNINGS[*]}" \
"ZFS Report" "warning"
fi
echo "━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━"
[[ ${#WARNINGS[@]} -gt 0 ]] && exit 1
exit 0