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19 Apr 2022

How to Reduce the Cost of Running a NAS

A home NAS (Network Attached Storage) is a staple for computer enthusiasts. No home computer lab is complete without one.

However, as energy prices continue to rise globally, this is the perfect time to consider how much a home NAS costs to run and importantly, share some advice with you on how to reduce these costs.

Before reading about NAS power consumption, we recommend catching up with this post, which explains how Hard Disk Drives (HDDs) work. This is because they're currently the main storage device used by a NAS.

How Much Energy Does a NAS Typically Use?

First, let’s look at how much energy a home NAS uses. In this example, we are assuming that the NAS will have 100% uptime for a year; assumption number two is that the NAS will use the same amount of energy consistently. We have used the April 2022 energy cap for UK electricity which, for most people, is what they are now paying per unit. You should consult your electricity provider for what you are being charged.

Days on per year365Days
Hours on per day24Hours
Annual Time On8760Hours
Cost of energy0.28 (0.37)£ (US$)

The table below shows the annual cost of running a 35W NAS:

Power consumption35Watts
Annual Energy Consumed306.6kWh per year
Annual Cost86 (113)£ (US$) per year

Increasing the power to 40W shows that even a slight increase in power consumption can have quite a drastic effect on the annual cost:

Power consumption40Watts
Annual Energy Consumed350.4kWh per year
Annual Cost98 (129)£ (US$) per year

How Can I Reduce the Cost of Running a NAS?

The above data tells us that there are three main ways to reduce the annual cost of running your NAS. Number one, reduce the cost of energy. Unfortunately, this one is out of your control. And with rising utility prices, it's not likely to happen any time soon.

But we can take a look at the remaining two possibilities. These are reducing the annual time on and the power consumption of your NAS. Here are some practical tips from us on how you can do both.

Reducing the Annual Time On of the NAS

Reducing the annual time on of your NAS is the easiest way to lower the annual cost of running it. Here, it's important to take 'drive spin down' and 'spin up' into account.

The peak power consumption of a HDD usually occurs when the drive is spinning up. Even though turning the NAS off will reduce the amount of power that the NAS uses over time, it's important to note that when the drives spin back up, they'll temporarily use more power until the HDDs reach their running speed. At which point, the power usage will be mostly consistent.

Spin down/up also puts more strain on the drive and may shorten the drive’s lifespan. We recommend that you check the disk manufacturer’s documentation for the start/stop count of the HDD. 

Reducing the Power Consumption of your NAS

The next way to reduce the annual cost of running a home NAS is to lower its power consumption.

Swapping the HDDs in a NAS for Solid State Drives (SSDs) will reduce the amount of power your NAS needs. However, SSDs are more expensive per gigabyte than their HDD counterparts. This can make the costs exorbitant for large amounts of data.

Optimise your HDD

If SSDs aren't suitable for your home NAS, then another thing you can consider is going for a 2.5 inch-HDD. HDDs require less power than their 3.5-inch counterparts and are more resilient to spin up/down. This makes 2.5 inch HDDs a good choice when the NAS is frequently powered down, or powering saving options like drive spin down are enabled.

SSDs can also be implemented as a cache in the NAS, enabling the HDD to spin down for longer periods of time, as data that is accessed frequently can be retrieved from the cache. A read-write cache also allows data to be synchronously written from the cache to the HDDs. This saves time when writing data to the HDD.

Reduce the RPM

The RPM of a HDD will also directly affect the amount of power that the drive requires. The higher the RPM of the HDD, the more power it'll need. However, reducing the RPM of the drive will increase seek time and reduce I/O performance. But, I/O performance is less important for a NAS disk than for a local/system disk. In a home environment, you may find that the transfer rate is bottlenecked by the network, especially over WiFi.

Swap Air for Gas in Your HDD

You might also want to consider the gases contained within the HDD. Conventional HDDs are filled with air (a mixture of oxygen, nitrogen and a small amount of carbon dioxide and argon). Air is an important part of a HDD, as the read/write head “rides” on a thin layer of air, preventing it from coming into contact with the platter and causing a head crash.

This is known as air bearing. Unfortunately, due to the speed that the platter spins at (usually 5,400 RPM and up), this causes a considerable amount of drag. This means it uses more energy to make the disk spin at these speeds.

Changing this air for a gas with a lower density like helium can reduce the amount of drag on the HDDs. In turn, this can lower the amount of energy needed to spin the disk.

Cut Down Your Disk Count

Reducing the number of disks stored within it and replacing them with larger-capacity disks will also reduce the power consumption of your NAS. It's important to bear in mind that the more platters a HDD has, the more power it'll need. This means you should bear in mind the number of platters when you're replacing several HDDs with fewer, high-capacity HDDs.

Reducing the number of disks in the NAS may also remove the ability to provide fault tolerance through RAID configurations like RAID 1. This can be offset by performing a backup of the data stored on the NAS.

Using Macrium Reflect, files on the NAS can be backed up over the network using a file and folder backup. You can read more about file and folder backups in this knowledgebase article. This blog post contains more information about the differences between RAID and backups.

Other Hardware Adjustments to Reduce NAS Power Consumption

So far, we've only looked at the effect of HDDs on your NAS' power consumption. But you should also consider the other hardware components. The amount and speed of the memory and the CPU in the NAS will also affect power consumption.

Consider the CPU

More memory requires more power to run. However, increasing the amount of memory can carry the bonus of decreasing the frequency of disk access. The CPU your NAS is using will also affect power consumption. Many NAS devices now make use of reduced instruction set command computer (RISC) CPUs like ARM CPUs. These CPUs have a lower power consumption than their x86-64 counterparts and can be a good choice for a NAS CPU.

You should also consider other factors that don't directly relate to the NAS. For example, if you need a network switch to connect the NAS to the network, you'll need additional power.

Be Smarter with Power

It's also important to note that the efficiency of your power supply will also affect the power draw of the device. The more efficient a power supply is, the higher percentage of power drawn from the mains will be delivered to the component. And the remaining energy will be lost as waste energy, such as heat.

For example, a power supply with an efficiency rating of 50% will need to draw 100W from the mains to deliver 50W to the connected components. We recommend reading this excellent article from Tom’s Hardware for more information about choosing the right power supply for you.

Monitor Your Energy Usage

A plug in energy monitor is a good investment. It'll allow you to evaluate the actual power consumption of your devices. Remember that most devices will have a variable power consumption. So it's best to measure accumulated power consumption over 24 hours. Don’t worry about the power factor - domestic power metres only measure the real power component.

Optimising Power Equals a Lower-Cost NAS

Over the course of a year, even the smallest of changes in wattage can add up. With rising utility prices taking effect around the globe, now is the perfect time to assess how much power your equipment needs and whether you can make small changes for the better.

Not only will you be reaping the benefits financially, you'll be doing your part to save energy and boost the eco-friendliness of your setup.

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