Its Safe to Spin Down Your Mechanical Hard Drives

Old Wisdom

I have read and been told in the past that you should never let hard drives spin down. They always claim that if you let them spin down, they will fail faster. As I gained experience in IT I noticed that to not be the case. Mechanical hard drives spinning down or not had no affect on lifespan. Some systems used it, some didn’t, both had drives fail at about the same rate.

When I set out to write this article, I expected to find a lot of sources one way or the other. I expected everyone to have come to a consensus on this. All I could find was opinions. It seems that no one has ever truly looked into this. Companies like Backblaze release quarterly reports on their fleet of hard drives ¹, but they don’t track or look into spin down counts. ²

Internet Opinions

On sites like Reddit, plenty share their thoughts but still no actual facts or data.

I have 2 arrays. One is accessed all the time. The other one is accessed maybe once a week. The first one never spins down. The 2nd one spins down between usage.

That being said, I would be more concerned with total power draw and noise levels, opposed to drive health. Even consumer drives are rated for years of use in various work settings. Just have a back-up in case of a sudden failure. Most drives will give you 5-7 years of use either way.
— H_Q_³

There’s no conclusive evidence one way or the other whether a spinning disk 24/7 or one turned on and off regularly is better or worse for it.

Maybe switching on and off dozens of times a day, just by nature of mechanical devices, isn’t the best thing for it. But if that alone will decrease its usable lifespan before it becomes irrelevant or fails for other reasons, there’s no way to say one way or the other.

All we do know is spinning 24/7 uses electricity that wouldn’t otherwise be used if not. Otherwise flip a coin, use your best judgement, and don’t worry about it. — HTWingNut⁴

If you do a full power on and off hundreds of times a day for years because of a bad configuration? Yeah, that’s probably a pathology. A long while ago when I looked into it, the ratings for the numbers of complete spinups from stopped is a lot less than the rating for the number of times the drive can “sleep”, parking heads and (possibly) reducing RPM.

However, hard drives are still perfectly fine being turned on and off multiple times (double digits) every day for years. This is what has been expected from them for decades… — [deleted]⁵

Power Savings

While people will argue about drive health impacts forever, the power savings of spinning down hard drives can not be disputed. My home Unraid server is a Dell PowerEdge T320 with 8 Mechanical hard drives and 1 NVME SSD. With the drives all spun up and idle, the server uses 126 Watts of power. With the drives spun down it only uses 70 Watts.

With Unraid I can put all of my frequently accessed stuff and Appdata on the always on NVME and let the mechanical drives power down.

My Opinion

It depends on the workload but, for less frequently accessed business items like backup storage, and almost all home servers, spinning down hard drives is worth it. There is no proven link between spinning down hard drives and failures. It’s also cheaper, which is never a bad thing.