add script to monitor disk power state

examples/disk-state.sh

@@ -0,0 +1,44 @@
+#!/usr/bin/env bash
+#
+# Watch disk power state (HDD spin-up and spin-down events).
+#
+
+# Arguments.
+disk='/dev/disk/by-id/ata-WDC_WD40EFRX-68N32N0_WD-WCC7K0CPF0N1'
+
+# Assert that this script is run as root.
+if [ "$(id -u)" -ne 0 ]; then
+  printf '%s\n' 'Error: This script has to be run as root user.' 1>&2
+  exit 1
+fi
+
+trap ctrl_c INT
+function ctrl_c() {
+  echo "End: $(date +"%Y-%m-%dT%H:%M:%S%z")"
+  exit 0
+}
+
+function notify-spin-down(){
+  while hdparm -C "${disk}" | grep 'active/idle' >/dev/null; do
+    sleep 15s
+  done
+  echo "$(date +"%Y-%m-%dT%H:%M:%S%z"): ${disk} has spun down"
+}
+function notify-spin-up(){
+  while hdparm -C "${disk}" | grep 'standby' >/dev/null; do
+    sleep 15s
+  done
+  echo "$(date +"%Y-%m-%dT%H:%M:%S%z"): ${disk} has spun up"
+}
+function main(){
+  echo "Start: $(date +"%Y-%m-%dT%H:%M:%S%z")"
+  hdparm -C "${disk}" | grep 'active/idle' >/dev/null && notify-spin-down
+  hdparm -C "${disk}" | grep 'standby' >/dev/null && {
+    while :; do
+      notify-spin-up
+      notify-spin-down
+    done
+  }
+  echo "${disk} has unknown state"
+}
+main