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Comment by jeffbee | Hacker News Reader

Why is hibernation even a thing? I can count the number of times I've wanted it on zero fingers.

I'd absolutely love to use it on my secondary machine, a desktop PC running Windows 10 – just hibernate and pick up right where I've been a few days later without leaving it in standby blinking its super bright LED aggressively. Sadly if I send it to hibernate the PC will always turn itself back on in the night, so no hibernate for me...

You should check `powercfg lastwake` via PowerShell, and Event Viewer, to determine what wakes up your PC.

I had similar issues, and IIRC, I had to disable wakeups for network adapters in Device Manager.

I've tried lots of things from the first page of google results but I don't think I've tried that. Will give it a shot for sure!

Thank you for this -- I've been bothered by my Windows PC not sleeping properly for the best part of a year. `powercfg lastwake` indicated the Ethernet adapter and then disabling the option "Wake on Pattern Match" has allowed the computer to sleep soundly.

I really do not understand Windows 10. It really seems like Windows 10 laptops and PCs are unable to sleep. They keep waking up, and then refuse to sleep. Frequently I find my work laptop in the morning turned on by itself, screen on, fan blowing enthusiastically. Power management in Windows 10 seems to be utterly broken. It certainly doesn't obey any of my settings.

Laptops, mostly, to maximize battery life. If I'm going on a flight, I'll charge and hibernate my system at home, bag it, then drive to the airport and get through security. This is about a 2 hours process and entails zero battery drain.

But what's the real value over a cold boot? Wake from hibernate takes a lot longer than a cold boot, and to me it doesn't seem to save any time.

You don't lose open apps, files, tabs, etc., so your work is not interrupted.

I've not perceived any time difference between cold boot and wake from hibernation, on a decently fast SSD.

Which OS are you using? I've never noticed a difference between cold boot and hibernate on Linux.

Are you sure you're including the amortized lifetime cost of whatever you had to do / whatever you will have to do to troubleshoot Linux resume-from-disk?

I kid, but I do use Linux, it's just a Linux that doesn't even offer hibernate and boots cold in one second: ChromeOS.

Anecdata: back in the days when I was using Ubuntu (pre-Unity) on what was even at the time moderately old hardware, there was an obvious difference. Standard bootup took 20-30 seconds, resuming from hibernation took multiple minutes.

Just thinking about it on an abstract level, it's not that unintuitive that resuming from hibernation should be slower than both cold boot and resuming from sleep. When you cold boot you need to load the kernel and startup programs into memory. With hibernation you need to load the whole previous operating state into storage, which is going to mean multiple GBs need to be read from your swap partition into memory. It's not hard to imagine that on many systems the hard drive will be the slowest piece of hardware.

But over suspend to RAM? Suspend to RAM eats through basically zero battery, and can trivially survive the plane flight. (I've taken my laptop on flights, drained the battery to <10% in the course of the flight, and had it spent the last several hours in suspend-to-RAM.)

(There might be some discussion about security in America's airports, and their overzealousness towards illegal searches, and on that basis, I'd entertain hibernation as superior.)

If you suspend to RAM, and there's some kind of failure, you lose everything, likely leaving some things in a bad state. Hibernation is way less likely to have something like that happen. Of course, the best of both worlds is Suspend then Hibernate.

What do you mean by lose everything? AFAIK, suspend syncs the disks so there really shouldn’t be any half-written data.

Everything being "the contents of ram and the running system image". Suspend to ram doesn't write the contents of ram to disk, it keeps the ram active, constantly refreshing it.

Hybrid Suspend will suspend to ram, then additionally write the contents of ram to disk, so that the image can be resumed in the event of a power failure. The "resume" codepaths in this case are literally the same as if you'd just hibernated.

I interpreted that as "syncs the disks", as in, flushes the buffers. (which it does, I believe, do.) A failure to suspend from RAM isn't that harmful: it's just an unscheduled reboot, as if you'd suddenly removed power.

The wording they're responding to is pretty vague: "lose everything". What is "everything"? E.g., the filesystem state is in good order. And even though RAM gets reset, many applications, like Firefox, will usually simply realize what happened, and recover.

I meant the system state when you suspended. You're absolutely right that it's just like an unplanned reboot, which isn't the worst thing in the world, but if (for example) you're doing funny things with tmpfs it can cause issues. Or, if you suspend habitually with unsaved progress, you would be in greater danger of losing it. Neither is enormously important, but it's worth noting.

On Linux with SystemD at least, suspend doesn't sync to swap unless you use suspend-then-hibernate, which involves getting hibernation set up. That's exactly what I do, though with a relatively short timer since my laptop is encrypted. Not that realistically anyone stealing my laptop would be able to extract the key if it was suspended, but I just like putting in the password in the stark, pre-boot environment.

You lose the running state, as if you'd pulled the battery out. I've had that only happen a few times, ever. Many applications nowadays recover from that. My editor has recovery files, many of my games autosave, my web browser restores the session, etc. It is disruptive, yes, but it's rare enough that I just don't care that much about it. (And definitely not enough that I'd trade the speed of suspend-to-RAM for the reliability of suspend-to-disk.)

(I've had far more issues with the physical connection between the laptop & the battery not being very solid anymore…)

To prevent a machine with full disk-encryption from having its key in memory while you're not watching it:

- With hibernation it is possible to store the hibernation file on the encrypted root partition so you will have to re-enter the password during boot.

- With suspend-to-RAM, it would always be in memory.

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