HDD Spindown Configuration via rc.local

Overview

HDDs can be configured to automatically spin down after a period of inactivity, reducing power consumption and heat. This guide uses hdparm with the -S flag to set idle timeout and ensures the setting persists across reboots using /etc/rc.local.

The hdparm -S 240 command sets the idle timeout to 20 minutes (240 * 5 seconds = 1200 seconds).

Step 1: Open rc.local File

Edit the /etc/rc.local file:

sudo nano /etc/rc.local

Step 2: Add hdparm Command

Add the hdparm command just before the exit 0 line. Replace /dev/sdX with your actual disk device:

#!/bin/bash
# Your other startup commands here

# Set HDD idle timeout to 20 minutes (240 * 5 seconds = 1200 seconds)
sudo hdparm -S 240 /dev/sdX

exit 0

Finding Your Disk Device

List all block devices to identify your HDD:

lsblk
# or
sudo fdisk -l
# or
sudo hdparm -I /dev/sdX | grep "Model"

Common device names: /dev/sdb, /dev/sdc, /dev/sdd, etc.

Step 3: Make rc.local Executable

Ensure the file is executable:

sudo chmod +x /etc/rc.local

Step 4: Enable rc.local Service (Ubuntu 18.04+)

Modern Ubuntu versions don't run /etc/rc.local by default. Create a systemd service file:

Create the Service File

sudo nano /etc/systemd/system/rc-local.service

Add Service Configuration

[Unit]
Description=/etc/rc.local Compatibility
ConditionPathExists=/etc/rc.local

[Service]
Type=forking
ExecStart=/etc/rc.local start
TimeoutSec=0
StandardOutput=tty
RemainAfterExit=yes
SysVStartPriority=99

[Install]
WantedBy=multi-user.target

Enable and Start Service

sudo systemctl daemon-reload
sudo systemctl enable rc-local
sudo systemctl start rc-local

Step 5: Reboot and Verify

Reboot the system to apply the configuration:

sudo reboot

After rebooting, verify the idle timeout is set correctly:

sudo hdparm -I /dev/sdX | grep -i idle

Expected output shows the idle timeout value set.

hdparm Spindown Values

The -S flag uses a specific scale:

Alternative: Using a systemd Service

For more control than /etc/rc.local gives you, define a oneshot systemd service that applies the setting at boot:

Create Service File

sudo nano /etc/systemd/system/hdparm-spindown.service

[Unit]
Description=Set HDD Spindown Timeout
After=syslog.target

[Service]
Type=oneshot
ExecStart=/usr/sbin/hdparm -S 240 /dev/sdX
RemainAfterExit=yes

[Install]
WantedBy=multi-user.target

Enable Service

sudo systemctl daemon-reload
sudo systemctl enable hdparm-spindown
sudo systemctl start hdparm-spindown

Monitoring HDD Activity

Check current HDD power state:

sudo hdparm -C /dev/sdX

Output will show:

• drive state is: active/idle - Currently active or idle
• drive state is: standby - Spun down

Monitor real-time disk activity:

iotop
# or
iostat -x 1

Troubleshooting

hdparm Command Not Found

Install hdparm:

sudo apt install hdparm

Service Won't Start

Check service status:

sudo systemctl status rc-local.service
sudo journalctl -u rc-local.service -n 20

Setting Doesn't Persist

Verify /etc/rc.local is executable:

ls -la /etc/rc.local

Device Not Found

Ensure the device path is correct:

sudo lsblk -o NAME,TYPE,SERIAL,SIZE

Power Saving Benefits

• Reduced power consumption: Inactive drives consume ~0.1W vs 5-10W when spinning
• Lower temperatures: Cooler operating conditions extend disk lifespan
• Quieter operation: Spindown reduces fan noise

Best Practices

• Don't set spindown time too short (causes excessive spin-up cycles)
• Monitor drives during spindown to ensure no data loss
• Use with backup drives or non-critical storage
• Test before production deployment