Add staggered drive spin-up script and systemd unit

12x 3.5" HDDs spinning up simultaneously can spike ~240W, pushing a single
750W PSU close to its limit. Two-layer fix:
- Layer 1: racadm iDRAC BIOS setting (HddSeq) fires at POST before OS loads
- Layer 2: stagger-spinup.service wakes drives one at a time via hdparm on boot

https://claude.ai/code/session_01TxTSnxDjgEVuNztdsWQjMD

scripts/stagger-spinup.service

@@ -0,0 +1,16 @@
+[Unit]
+Description=Stagger hard drive spin-up to limit PSU current surge
+# Runs early in boot, before storage services and VMs start, so drives
+# are already spun up and staggered before any heavy I/O begins.
+DefaultDependencies=no
+After=local-fs-pre.target
+Before=local-fs.target sysinit.target
+
+[Service]
+Type=oneshot
+ExecStart=/usr/local/sbin/stagger-spinup.sh --linux
+RemainAfterExit=yes
+StandardOutput=journal
+
+[Install]
+WantedBy=sysinit.target

scripts/stagger-spinup.sh

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+#!/usr/bin/env bash
+# Stagger hard drive spin-up on Dell R730xd to avoid PSU current surge at boot.
+#
+# 12 x 3.5" HDDs spinning up simultaneously can spike ~240W for 2-3 seconds.
+# Staggering them 2-3 seconds apart keeps the surge well within PSU limits.
+#
+# TWO layers of protection:
+#   1. iDRAC BIOS setting — fires at POST, before the OS loads (preferred)
+#   2. Linux systemd service — staggers drives that weren't spun up at POST
+#
+# SETUP
+# ─────
+# Layer 1 (iDRAC, run once):
+#   bash stagger-spinup.sh --idrac
+#   # Requires racadm and iDRAC network access, then reboot to apply.
+#
+# Layer 2 (Linux service, run once):
+#   cp stagger-spinup.sh /usr/local/sbin/stagger-spinup.sh
+#   chmod +x /usr/local/sbin/stagger-spinup.sh
+#   Install the systemd unit below, then:
+#   systemctl daemon-reload && systemctl enable stagger-spinup.service
+
+set -euo pipefail
+
+STAGGER_SECONDS=3   # delay between each drive spin-up
+HDPARM=$(command -v hdparm || true)
+
+# ── iDRAC BIOS method (Layer 1) ───────────────────────────────────────────────
+
+configure_idrac() {
+  if ! command -v racadm &>/dev/null; then
+    echo "racadm not found."
+    echo "Option A: Run from iDRAC SSH:"
+    echo "  ssh root@<idrac-ip>"
+    echo "  racadm set BIOS.StorageSettings.HddSeq Enabled"
+    echo "  racadm jobqueue create BIOS.Setup.1-1"
+    echo "  # Then reboot to apply."
+    echo ""
+    echo "Option B: iDRAC web UI:"
+    echo "  System BIOS → Power Management → Hard Disk Drive Sequencing → Enabled"
+    echo "  Apply and reboot."
+    return 0
+  fi
+
+  echo "Enabling iDRAC hard disk drive sequencing (staggered spin-up)..."
+  racadm set BIOS.StorageSettings.HddSeq Enabled
+  racadm jobqueue create BIOS.Setup.1-1
+  echo "Job queued. Reboot for the BIOS setting to take effect."
+  echo "Verify after reboot with: racadm get BIOS.StorageSettings.HddSeq"
+}
+
+# ── Linux spin-up stagger (Layer 2) ──────────────────────────────────────────
+# Called by the systemd service early in boot.
+# Reads each block device in sequence with a short delay, causing drives in
+# standby to spin up one at a time rather than simultaneously.
+
+stagger_linux() {
+  if [[ -z "$HDPARM" ]]; then
+    echo "hdparm not found — apt install hdparm"
+    exit 1
+  fi
+
+  mapfile -t drives < <(lsblk -dn -o NAME,TYPE | awk '$2=="disk"{print "/dev/"$1}' | sort)
+
+  if [[ ${#drives[@]} -eq 0 ]]; then
+    echo "No block devices found."
+    exit 0
+  fi
+
+  echo "$(date): Staggering spin-up for ${#drives[@]} drives (${STAGGER_SECONDS}s apart)..."
+
+  for dev in "${drives[@]}"; do
+    # Skip if device is already active (check power mode)
+    state=$($HDPARM -C "$dev" 2>/dev/null | grep -oP '(?<=drive state is:  )\S+' || echo "unknown")
+
+    if [[ "$state" == "standby" || "$state" == "sleeping" ]]; then
+      echo "$(date):  Waking $dev (was: $state)"
+      # A zero-length read is enough to trigger spin-up
+      dd if="$dev" of=/dev/null bs=512 count=1 status=none 2>/dev/null || true
+      sleep "$STAGGER_SECONDS"
+    else
+      echo "$(date):  $dev already active (state: $state) — skipping"
+    fi
+  done
+
+  echo "$(date): Stagger complete."
+}
+
+# ── Argument dispatch ─────────────────────────────────────────────────────────
+
+case "${1:-}" in
+  --idrac)
+    configure_idrac
+    ;;
+  --linux|"")
+    stagger_linux
+    ;;
+  *)
+    echo "Usage: $0 [--idrac | --linux]"
+    echo "  --idrac   Configure iDRAC BIOS staggered spin-up (one-time setup)"
+    echo "  --linux   Stagger drives via hdparm now (run by systemd service)"
+    exit 1
+    ;;
+esac