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My secondary hard-drive (platter) sometimes has a lag of 1-5 seconds when it hasn't been accessed in a while, causing explorer or other software to stutter.

Reading online, I saw the advice that you should change it so the hard drive never turns off using this setting:

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Is that relatively safe to do?

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    I'm more curious if a normal windows computer with multiple programs running ever enters a state when HDD is not used, even if OS is on extra SSD. – Tomáš Zato Jun 6 at 12:47
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    If you have enough RAM, that should be possible. Programs only read directly from RAM (regardless of OS), so if you're not using giant files, you could theoretically run just with RAM. I'd expect something like web browsing, and even small downloads to be fine without the HDD. – Cullub Jun 6 at 14:44
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    This is my secondary harddrive, so it's when I go to access data files, not programs. – JoshuaD Jun 6 at 17:35
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    I've been leaving all my desktop systems running 24/7 for years (decades, actually), and have always disabled power savings on hard drives. I've only had one HDD fail in the last 20 years and that was on a laptop that did power down the drives. – Carey Gregory Jun 7 at 0:42
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    Is turning off hard disks harmful? and How harmful is a hard disk spin cycle? - the only consensus is that there's no consensus. 20 plus years ago this was worth debating; I don't think it is anymore. – Mazura Jun 7 at 0:54
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Yes, this is perfectly safe.

The advantage of powering mechanical drives down when not in use is simply to save electricity. Mechanical drives typically draw between 5 and 6 watts. You can look at your electric bill and see how much your power company is charging you per watt-hour and get an estimate on how much more it will cost you to leave it on. It isn't much.

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    Also, just because it is on, doesn't mean it is spinning or at least spinning at full RPM. It will still have a low power mode that will consume less wattage when not in actual use. – Jammin4CO Jun 6 at 14:00
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    @Jammin4CO: Low-power / non-spinning but still "on" is what this setting is all about. It doesn't literally cut power to the HD's power connector; the controller stays on and it leaves this state by simply sending a SATA command. – Peter Cordes Jun 6 at 14:48
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    Do they really have hard drives that spin at a lower RPM to save power? – JPhi1618 Jun 6 at 20:01
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    @JPhi1618 just found this PDF from Seagate describing such a power saving measure. Seems to be more of an enterprise feature. – Nick Jun 6 at 20:26
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    @JPhi1618 WD Green drives were initially marketed as variable-RPM drives, but they ended up only including that feature on a few specific models. The rest were just crappy 5400 RPM drives in a desktop form factor, when everyone else was building 7200 RPM or 10000 RPM drives. – FeRD Jun 7 at 7:30
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Yes, it’s safe but it has its disadvantages.

1.- Shorter life span

Due to constant spinning mechanical parts will start to fail earlier. This is just how stuff works, things wear, tolerances broaden, things break. Most popular brands of hard drives will last a long time, if you take care of them. My thoughts on this, is have one small fast drive for the work and large drives for storage, which will be powered down most of the time. This way you use them efficiently.

2.- Damage to platters

If bumped when when mechanical parts are moving then you will risk irreparable, way too expensive, damage. Some laptops have an accelerometer that deactivates the HDDs, or move the heads away, when it's in free fall. I don’t know if this feature is available for desktops, or servers.

3.- Electric bill/ Laptop battery

It will draw more power, plain and simple. The power consumption will vary according to physical size, storage technology, etc; but in the end it is going to take its toll on your bill, or battery.

Do it if you need to, otherwise leave it be: it's just a couple of seconds.

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    @Navin Seconded: This is why servers which have been powered on for months / years, will often lose a HDD after a power-outage. – SiHa Jun 6 at 10:58
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    #2 also seems irrelevant, since active hard drive protection (if present) is unlikely to be affected by the turn-off-when-idle setting the OP is asking about. (Well, except that if the drive happens to be already off — and the head parked — when it's dropped, then it may survive even if the active protection fails. But that's not something one should rely on.) – Ilmari Karonen Jun 6 at 12:09
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    For #2, no - active protection is a laptop thing only. If your server or desktop finds itself in free-fall while powered on and operating then you probably have bigger problems on your hands. #1 is just wrong. – J... Jun 6 at 14:13
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    @J... No it's not wrong. Drives have two lifetimes, one is a lifetime on how many hours it can spin from e.g. bearing wear and aerodynamic wear of the heads floating on the platters. The second lifetime is the wear from unloading the heads, either as they touch down on the platter or they pull off on a ramp. Exceeding either lifetime can cause a drive to fail, this is why SMART monitors start/stop cycles and spinning hours. – user71659 Jun 6 at 17:44
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    In my experience, your point #1 is flat wrong: a hard drive is most likely to fail during spinup. An always-on hard drive will last longer than one that's constantly being spun up and down. – Mark Jun 6 at 20:20
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Yes, this option is only designed to save electricity. In fact, spin-up/spin-down count is a much stronger indication of wear and tear than actual time spent spinning. Hard drives are designed to spin up and stay spinning; constantly spinning them up and down actually damages the drive more than keeping it spinning. See Is turning off hard disks harmful?

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