Sleep vs Hybernate?

B

Bob Newman

I would like someone's opinion a little more knowledgeable than mine. Is it
necessary to hibernate (save wear & tear on the computer) instead of sleep?
Saving energy is not a priority, saving my computer is. I am under the
impression that my scheduled night time backups will run in sleep but not
hibernate modes. Is this correct?

Bob
 
R

Randem

in Hibernation mode, nothing will run. The state your computer was in will
be saved to the HD and retrieved when you press the power button. Your
computer is actually OFF. In Sleep/StandBy mode your computer is in a low
power mode and can be awaken by the movement/activation of a device.

--
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G

Guest

None electrically. But in hebernate the memory is saved to a file then the
machine turns off.
 
R

Randem

The big difference is that in Hibernation mode when you turn the machine
back on it will go to the exact state it was turned off, IE. any program
loaded will be reloaded to the point where it hibernated. With turning the
machine, you have to start all over again. No programs will be running.

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N

Nate Grossman

Randem said:
The big difference is that in Hibernation mode when you turn the machine
back on it will go to the exact state it was turned off, IE. any program
loaded will be reloaded to the point where it hibernated.
Click to expand...

And it will do so much faster than if you started from OFF.

With turning the
machine, you have to start all over again. No programs will be running.

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Click to expand...
 
P

Paul

Bob said:
I would like someone's opinion a little more knowledgeable than mine. Is it
necessary to hibernate (save wear & tear on the computer) instead of sleep?
Saving energy is not a priority, saving my computer is. I am under the
impression that my scheduled night time backups will run in sleep but not
hibernate modes. Is this correct?

Bob
Click to expand...

The ACPI states are mentioned here.

http://en.wikipedia.org/wiki/Acpi

The ones of note might be

S1 Standby (mainly monitor power savings - fans still spinning)

S3 Standby suspend to RAM. Session stored in RAM. Fans off. +5VSB running.
If the computer is switched off at the back by accident, the contents
of RAM are lost. A fresh boot would result at the next session.

S4 Hibernate. Session stored on disk. Fans off. +5VSB running.
If the computer is switched off at the back by accident, the hiberfile is
still there. (I haven't tested my current computer, to see if the hiberfile
gets used on a reboot after a complete power failure.)

G3 Mechanical off. +5VSB is no longer running. RTC runs from the CMOS battery.

How the ATX power supply works, is like this.

---- AC_Input --- rectified_DC ---+---- +5VSB power conversion
| (Standby power source, some power waste)
|
+---- +3.3/+5/+12/-12 power conversion
Fans spin when running
Main power source for computer

If you use S3 or S4, then the upper power conversion section is
still running. Hibernate doesn't really need it, as the session
is stored on disk. S3 Suspend To RAM does need the +5VSB power,
to power the RAM sticks while they're self-refreshing.

The power supply may use 5-10W (a guess) when +5VSB is being provided,
and some of the chips that have wake up capabilities, need some
power to do their job. For example, a computer with "Wake On LAN",
may consume 300mA current flow to the LAN chip, in order for the
magic packet to be recognized when it is received. So the WakeUp
capable circuits still need some power, if they're to wake the computer.

Removing all power (G3) is the least stress, as then the AC
is disconnected via the switch on the back of the computer.
It will wear down your CMOS CR2032 battery faster though. The
battery is not allowed to be charged by the computer, and the
RTC (real time clock) has fairly low power needs (several microamps).
The RTC will use the battery, during G3. The RTC uses +5VSB derived
power, in S3 or S4, or during regular operation.

Using G3 (mechanical off) is not going to allow scheduled tasks to
run. But one of the other states, that allows the machine to wake up,
might be suitable.

I don't really see a lot to get excited about, in the above
description. S4 takes a bit of time to recover from. S3 means
you have an exposure to a power failure. In S3 or S4, the upper
half of the power supply is still running, but there is no fan to
cool whatever heat is thrown off.

Paul
 
J

Jon

Hi,

Although this doesn't answer your question fully, let me explain the difference between shutdown,
hibernate and sleep...

If you shut down your PC, it closes all of your programmes (eg Word, Firefox) if you haven't done so
already, then turns itself off. When you turn your PC back on again, you have to re-launch all of
your programmes.

If you hibernate, it doesn't actually close your programmes, but instead saves their "state" to the
hard disk, then turns itself off. When you turn your PC back on again, the PC recovers the "state"
of all the programmes, and what you see is exactly what you saw before you hibernated - all the
programmes that you were running previously and with all the documents open as they were before, and
even with the cursor at the same position in (eg) your Word document. It also generally starts your
PC quicker than if you started it up after shutting it down first.

If you sleep, the PC powers down as much as it can (monitor, hard disk, and a few other things) but
doesn't power down the memory, which saves the "state" of all your programmes. When you turn your PC
back on again, the PC still has the "state" of all the programmes, and what you see is exactly what
you saw before you hibernated - all the programmes that you were running previously and with all the
documents open as they were before, and even with the cursor at the same position in (eg) your Word
document.

In both shut-down and hibernate, you can actually unplug your PC from the mains (and disconnect the
battery if you have a laptop) and all will be OK when you power up again.

In sleep, you must not unplug the mains/remove the battery, otherwise the programme state will be
lost, and you will lose the changes of any unsaved documents. There is also a small risk that you
may corrupt Windows in some way if you do this, although this is fairly unlikely.

Shutdown and hibernate use the least power (called "standby power") which is identical for both
modes, and use zero power if you actually unplug your PC from the mains.

Sleep uses more power, although usually it is pretty low, especially for a laptop.

Modern computers are designed to cope with being shut down, hibernated and set to sleep, so unless
you're doing this every hour or less, I wouldn't worry about wear and tear in any of the three ways.

Good luck,

Jon


I would like someone's opinion a little more knowledgeable than mine. Is it
necessary to hibernate (save wear & tear on the computer) instead of sleep?
Saving energy is not a priority, saving my computer is. I am under the
impression that my scheduled night time backups will run in sleep but not
hibernate modes. Is this correct?

Bob
 
J

John John - MVP

3c273 said:
Scheduled tasks will wake the computer from hibernation. Off is off.
Click to expand...

No, scheduled task cannot take the computer out of hibernation because
hibernation is also *off*.

John
 
3

3c273

I think you are confused ;-) From the "Microsoft Windows XP Professional
Resource Kit Documentation"
Sample chapter can be found at
http://www.microsoft.com/mspress/books/sampchap/5566d.aspx
Scroll down to the section labeled "Enabling Devices to Wake the Computer".
<quote>
On ACPI-compatible systems, Windows XP Professional can enable some devices
to wake the system from the hibernation or standby.
</quote>
I believe that you need to have one of your devices configured to be able to
wake the machine, such as wake on LAN. I read somewhere that WOL is the
mechanism used to do this but I can't find a reference. At any rate, I am
quite sure that my machine comes out of hibernation every morning or else I
wouldn't still have my job as my computer is my alarm clock and I manually
hibernate it every night.
Louis
 
J

John John - MVP

No, it isn't funny, it just can't happen. The article is wrong, the
author used the wrong term to describe what he is doing, he is waking up
a sleeping machine, a machine on stand by, he doesn't show in his
article how he got the machine to the sleeping state to later "wake" it
up. A hibernating computer is turned off. Hibernate saves everything
in the RAM to a file on disk (hiberfil.sys) and then it *completely*
shuts down the computer, when the computer is restarted the hiberfil
file is sucked back into memory and the Windows session is restored to
the state it was when it was hibernated. Other than saving the RAM to
disk hibernate does the very same thing as shutting down the computer.

The ntldr boot loader has special code in it and when the computer is
booted it looks for the hiberfil.sys file in the root of the boot
volume, if ntldr finds this file it sucks it into memory and returns the
computer back from hibernation. If ntldr doesn't find an hiberfil.sys
file it parses the boot.ini file or looks for the Windows installation
and it boots Windows normally. An hibernated computer is turned off, it
cannot be turned on by any Windows feature because Windows is completely
knocked out when the computer hibernates. Look in your Windows help
files for more information.

John
 
3

3c273

Microsoft disagrees with you. From the "Microsoft Windows XP Professional
Resource Kit Documentation"
Sample chapter can be found at
http://www.microsoft.com/mspress/books/sampchap/5566d.aspx
Scroll down to the section labeled "Enabling Devices to Wake the Computer".
<quote>
On ACPI-compatible systems, Windows XP Professional can enable some devices
to wake the system from the *hibernation* or standby.
Happens every day at my house. Look beyond the windows help files for more
information.
Louis
 
E

Emry

Hi;

Interesting expose of different power levels, especially for a novice
news-group user like me.

Have a question about relating to this when using a 3 year old comp with Win
XP. When I click Turn Off Computer the next window has 3 options: Turn Off,
Re Start, Stand By; the last blanked out so SB does not function. Any
solutions?
Thanks..Emry
 
J

John John - MVP

Wake on Lan has nothing at all to do with Windows, a computer that is
turned off cannot be awaken by the knocked out Windows on the same said
computer, the magic WOL packet has to be *sent* to the sleeping machine.
The option to turn on WOL on the adapter from within Windows simply
changes the option in the adapter firmware to enable it to accept WOL
packets. This has nothing to do with Windows or hibernate at all.

John
 
J

John John - MVP

Microsoft doesn't disagree with me, or I should rather say that I don't
disagree with Microsoft. You are misinterpreting what is mentioned in
the resource kit, these ACPI features can wake the system from
*hibernation* or standby, these ACPI features would be things like WOL
or Wake on Ring. There is *absolutely no way* that you are waking up a
hibernating computer with a Scheduled Task! The only way that could
happen would be for a scheduled task on *another* computer to send a
wake up call to the hibernating computer, the Windows installation on
the hibernating computer absolutely cannot bring the computer out of
hibernation, standby yes, hibernation, no.

From Microsoft:

"Like sleep, hibernate is a power-saving state. In Windows Vista, sleep
saves your settings in memory and draws a small amount of power to
maintain that memory. Hibernate, on the other hand, writes your settings
and the content of memory to the hard disk and then completely powers
down the system."

http://technet.microsoft.com/en-us/magazine/2008.05.sustainablecomputing2.aspx

Same thing for Windows 2000 and Windows XP, the system is completely
powered down after the hiberfil.sys file is written, scheduled tasks are
no longer available and Windows cannot reawaken itself from a powered
down state, something else has to initiate the power up.

John
 
P

(PeteCresswell)

Per 3c273:
That's funny, because my computer wakes me up every morning from
hibernation. I even woke up early the other morning and watched it. Perhaps
you're not doing it right.
http://blogs.techrepublic.com.com/window-on-windows/?p=828
Click to expand...

I suspected that somehow my PC can be awakened from hibernation.

I say this bc when it's in whatever mode it's in, all the power
lights are off and I have to hit the "on" switch to wake it up.

In various sleep modes I've used, the power lights never went all
off.

Mine wakes up every morning in response to Windows Home Server
wanting to back it up.

OTOH, I just did a search and could not find a "hiberfil.sys" on
any of the drives; so I'm probably wrong... but it sure *looks*
dead.
 
J

John John - MVP

There again, the author is confusing hibernate with standby, read his
post carefully:

"So, here is my workaround: Keep the PC in Hibernate (Suspend) mode and
wake it up at 6:00am."

Read more of his code and you will see that his code is relying on
Windows APIs and function calls to "wake up" the computer, he is missing
the fact that the hibernating computer is *turned off*, he has the
terminology mixed up. You can no more wake up an hibernating computer
with this code than you can one that is powered off without hibernate!

"Suspend" mode is NOT hibernate, you can search all you want on the
internet it will not change facts, a hibernating computer is powered
off, that is how hibernation works, the Windows session resumes when
ntldr reads and loads the hiberfil.sys file. I don't care what you say
or what any article on the web says you are simply not using Windows on
the powered off computer to turn it on, that is simply impossible. The
powered off computer can be turned on by other means but it cannot be
done by by Windows when Windows isn't running! People are confusing
Standby with Hibernate.

John
 

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