25 October 2022

Running an Energy Efficient Unraid Server

This blog goes over some best practices, tips + tricks, and build basics for users to run their Unraid servers in the most energy-efficient way possible.

Power Efficiency

With the state of global electricity prices, (especially in Europe), running an energy-efficient Unraid server is more relevant than ever. In this blog, we’ll go over some best practices, tips + tricks, and build basics for users to run their servers in the most energy-efficient way possible.

Why Care?

Global electricity prices are on the rise and are expected to rise even more. This means more monthly costs to run your Unraid homelab.

How much more are we talking?

USA: Average price per kWh: $0.167

50W idle cost: $73.20 per year

100W idle cost: $146.39 per year

150W idle cost: $219.20 per year

EU: Average price per kWh: €0.2192

50W cost: €96.41 per year

100W cost: €192.80 per year

150W cost: €289.20 per year

Avert your eyes, German users. 😩

Running an energy-efficient Unraid server also means a cooler and quieter server.

You can easily track your server’s power consumption with a UPS. The power load can be viewed via the Dashboard tab of the Unraid webGUI:

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How to Run a More Energy-Efficient System

Choose Power-Efficient Hardware Components

For the purpose of creating a power-efficient homelab, ignore the TDP numbers on hardware specs: Low idle server wattage is what you'll want to focus on.

Don't Buy Old Hardware

Hardware that is more than 8-10+ years old may be cheaper now but due to power inefficiencies, it will likely be more expensive to run in the long run.

Example: Older CPUs run at a much higher wattage at idle.

Intel vs AMD?

Intel tends to be more efficient at idle.

Where is a good place to find hardware power consumption info?

Hardwareluxx is a German forum with tons of great info on this topic.

Most Economical Systems Spreadsheet

Hardwareluxx has a google sheet full of great idle power stats for CPUs, Motherboards, GPUs, and more!

Power Supplies Matter

Choosing an energy-efficient power supply also helps! Most modern PSUs don't run very efficiently at lower loads so consider something like the Corsair RM550x PSU or look into potentially using a PicoPSU combined with a laptop power brick, if applicable to your server specs and use case.

Drive Storage Decisions

There are power tradeoffs when choosing between 5400 rpm vs 7200 rpm hard drives:

Transfer Speeds:

  • 5400 rpm ~100 mb/s
  • 7200 rpm ~120 mb/s

Power Consumption and Life Span:

Generally speaking, 5400 rpm drives tend to have lower energy consumption and a longer lifespan.

  • 7200 rpm hard drives will also run louder and hotter.

To Spin Down Drives or Not?

The age-old question: should you spin down your drives when not in use? It's a bit of a controversial topic. Some people claim this will add wear to the drives while others claim that no noticeable wear occurs on modern HDDs. 

If you decide to spin down, your hard drive power consumption can go down from 3-8 watts idle on average to 0.4 watts (per hard drive) so depending on how large your Array is, you might see large power efficiency gains when spinning down.

Note: spinning down hard drives might show a noticeable lag time in accessing data on spun-down drives. This is due to the drives needing time to spin back up before use and this lag will be more noticeable on 7200 rpm hard drives.

If you wish to spin down drives, head to Settings→ Disk Settings from the webGUI:

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Multiple Cache Pools

Since Unraid 6.9, multiple cache pools support allows you to write files directly to SSD cache pools and then later move those files to hard drives for the best performance experience. Using tiered caching is a great strategy alongside using more energy-efficient hardware and settings.

Want to Learn More?

Here is an excellent video from Wolfgang’s Channel on Youtube talking about a lot of these same server energy efficiency concepts in depth:

Processor Package and Core C-States using PowerTOP

PowerTOP is a software utility designed to measure, explain and minimize a computer's electrical power consumption.

Unraid forum moderator @mgutt has written a nice guide for reducing power consumption using Powertop with Unraid ⤵

Reducing Energy Consumption with PowerTOP

Learn how to optimize Unraid server power consumption with PowerTOP.

Generally, if your server can reach C8 idle, it will run the most efficiently.

Using the Tips and Tweaks Plugin: CPU Governor

Available via Community Apps, the CPU Governor in the Tips and Tweaks plugin will reduce your CPU's power usage. This plugin allows you to adjust the CPU Governor as well as set a lower power mode on a schedule for when your server is not in use.

To enable, set the CPU Governor by default to "Power Save" via the settings:

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Power Usage Reductions via NVIDIA GPUs

@SpaceInvaderOne has a nice video on how to reduce power usage on Unraid servers with Nvidia GPUs ⬇

Other Power-Saving Tips:

  • Don't use RAID/HBA cards. Instead, search for a board with as many SATA ports as needed (which are not provided by additional SATA controllers).
  • Prefer SATA cards over HBA cards.
  • Prefer 10G SFP+ passive DAC over 10G RJ45.
  • Prefer boards/CPUs with PCIe 3.0 over PCIe 4.0 or even PCIe 5.0.
  • Prefer iGPU over dGPU if you only want to transcode video content and don't need the dGPU inside a VM.
  • If you have a backup Unraid server, completely powering it off and only running it when a backup is required will save money.
  • Prefer containers over VMs.
  • Prefer air cooling over water cooling.
  • Use the least amount of fans as possible.
  • Use passive CPU coolers.
  • Prefer SSDs over HDDs.
  • Prefer /mnt/cache over /mnt/user for appdata and docker paths (avoids FUSE overhead).
  • Prefer disk shares over user shares (avoids FUSE overhead).

A special thanks to mgutt, Wolfgang, Spaceinvader One, dlandon, kizer, ChatNoir, JorgeB, Squid, and bonienl for input and/or creating content linked on this blog.

Do You Have Other Tips?

If you have other energy efficiency tips and tricks or can share knowledge on this topic, please do so in the forums!

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