Question could a system's HDD spin up when you tell system to go to sleep?

[GunsMadeAmericaFree]

I just put together a Ryzen 5 5600G based Windows 11 system. It is pretty snappy, and I've noticed that it seems almost completely quiet. However, I've noticed one thing that I didn't expect whenever I'm finished using it and I put the system to sleep. When I do this, I seem to hear something spin up louder, only for everything to then go silent. The system has an M2 SSD for the primary boot drive, but I've added a 4TB HDD for additional storage for games, backups of the last 15 years of our family photos, etc. I haven't done anything to the HDD yet, other than partitioning & quick formatting it so that Windows 11 can see it.

Would an HDD that has "spun down" after a while because it isn't being used always "spin back up" right before you put a system to sleep? Or would this more likely be the cpu fan? I wasn't expecting anything to get louder when telling everything to essentially take a nap.

 

[VirtualLarry]

probably flushing that disk's write cache, before going to sleep mode. At least, if I designed an OS, that's what I'd do.

 

[In2Photos]

I notice the CPU fan on my laptop spins up when I put the laptop to sleep. Could also be the HDD as Larry mentioned. Either way, not too concerning.

 

[GunsMadeAmericaFree]

I notice the CPU fan on my laptop spins up when I put the laptop to sleep. Could also be the HDD as Larry mentioned. Either way, not too concerning.

Ok, I was just wondering what the noise was, and hoping that the HDD wasn't spinning up from sleep, only for the system to go to sleep. Kind of like waking your kids up, only to tell them that it's time for bed!

 

[mikeymikec]

Would an HDD that has "spun down" after a while because it isn't being used always "spin back up" right before you put a system to sleep?

Yup. I've often encountered it on Windows, but on Linux I think the HDD stays spun down. As it's easy for me to verify in the OS that the HDD is asleep, I'll try to get around to testing whether it stays spun down during the sleep transition.

- edit - Mint 21 does not spin the (non-boot) HDD back in my system before transitioning to sleep mode. One difference though between Windows and Linux on the default settings is that Windows uses 'hybrid sleep': as a backup precaution it backs up the contents of RAM to disk (the hibernation file IIRC) before the sleep transition so that if power is lost during sleep mode, the system can recover more gracefully. AFAIK Linux does not do that, sleep just instructs the system to go into sleep mode. Therefore I wonder if Windows also perhaps does some kind of file system tidy measure on all connected storage volumes before the transition as well, causing a data drive to come back online only to be switched off again shortly. I would have thought it would be more logical to instruct a drive that's about to go into sleep mode to do whatever file system tidy measure first, so therefore if the rest of the system is put to sleep, the drive doesn't need to be brought online first. Having said all of that, I'm aware that Linux and Windows spins drives down differently: Linux relies on the drive's APM function to handle itself whereas Windows explicitly tells the drive to switch off (I'm not sure how exactly though). It's the reason why I switched to an APM-capable HDD in my system, so Linux could instruct the drive's APM and my data drive would switch off when it's been idle for a reasonable length of time.

As you and others suggested though, fans will sometimes rev up before the system goes into sleep mode. However, HDDs in my experience have a particular whine to them which is easy to tell that it's not a fan.