Hibernation Mode Vs. Stand-By (Sleep Mode)

[Inky]

I noticed a discussion thread last night where people were wondering about the difference between SLEEP mode (aka STAND-BY) and HIBERNATION.

When I recently got my T42 I wanted to know the difference--so much so that I actually called IBM and opened up a trouble ticket where the issue to resolve was my confusion about the difference between the two.

Instead of burying the results in the middle of that other discussion thread, I thought a post like this one would catch the eye of anyone who really wants to clearly understand the difference.

First off, to clarify WHAT we're talking about:

HIBERNATION is the Fn-F12 key combination.

STAND-BY (aka SLEEP) is the Fn-F4 key combination.

There is also the Fn-F3 key combination (on my T42 at least) which just turns the SCREEN OFF.

So, that's actually 3 modes. Here's how they differ:

SCREEN OFF = screen is off, but hard drive is still spinning, CPU and RAM are still active.

STAND-BY or SLEEP = Screen is off AND hard drive is off (stops spinning) but CPU and RAM are still active.
(Incidentally, I think everyone used to call it SLEEP which is why the F4 key has a little picture of the crescent moon on it, but recently Microsoft has started calling it "Stand-By" which actually makes sense, because that helps distinguish it from "hibernation" which sounds confusingly similar to "sleep".

HIBERNATION = Everything is off. Screen, HD, CPU, & RAM.


All three modes save SOME power because in each mode something has been shut off.

All three modes take you back to where you left off. If you were in the middle of word processing a letter that's exactly where you'll be when you resume.

The differences are in:
1. HOW MUCH power they save
2. HOW QUICKLY you can resume where you left off.

Here's how they stack up:

HIBERNATION saves the most power because it shuts everything off. It takes a snapshot of what's in RAM and saves it on the Hard Drive in a "Hibernation file". When you come out of Hibernation it uses that file to restore the RAM contents the way they were (which reflects what you see on screen).


STAND-BY uses a tiny bit of power to maintain the contents of RAM. Both the RAM and CPU are left active. When you resume from Stand-By it only has to power on the hard drive and the screen. For that reason coming out of Stand-By is roughly ten seconds faster than coming out of Hibernation.

And of course, resuming from "SCREEN OFF" is the fastest--you can resume instantly--because the hard drive never stops spinning, but for that reason it also saves the least power of the three modes.

Knowing these facts, how do you decide which to use when? I can only offer my own decision making strategy:

Because keeping the RAM and CPU active in STAND-BY does draw a tiny bit of current, it will reduce your available battery time slightly, and if you use STAND-BY a lot (all day or all night), then the added wear on your battery can cause a slight reduction in your battery's life span (All usage affects the battery's life span when there is a battery present--even if you're plugged into AC). Back when CPU speeds, RAM speeds and bus speeds were MUCH lower, the power used in STAND-BY mode was negligible, but with today's CPU, RAM & Bus speeds the power they draw has increased a bit.

Knowing that and weighing it against the faster resume time you get with STAND-BY here is the rule of thumb I finally settled on:

If I need to shut down, but I'm sure I will resume working on my ThinkPad very soon (within an hour) I use STAND-BY

If I think I might not resume working on the ThinkPad for more than an hour, then I use HIBERNATION.

My thinking is this: coming back from Stand-By is roughly ten seconds faster, but that time savings feels significant only if I am frequently stopping and resuming work within a short span of time.

If I stop working on the ThinkPad for a whole HOUR then relative to such a long interuption what's an extra ten seconds? Not much.

So, I use STAND-BY only for brief interuptions. Overnight I always use HIBERNATION.

When to use the SCREEN-OFF feature? Probably when you're operating on battery power (not AC) and want to be fanatical about saving battery usage.

For instance, even while you are working on the ThinkPad, if you need to say, just look at some papers or something for a minute or two, you could use the SCREEN-OFF toggle to save the battery a few minutes worth of backlight usage. The next step down from that, in power savings, is to just keep the screen as dim as possible.

Anyway, I hope that helps!

-Inky
P.S. Since I'm doing all my writing with the TP now instead of a pen, maybe it's time to change my name.

[Ground Loop]

There is one option you haven't considered.. suspend with an automatic hibernation after XX minutes.

So if you originally suspended it, and then left it alone for too long, the laptop can wake up, resume, and immediately hibernate. I think this is an IBM Power Manager feature, not a Windows XP feature.

Also, the time it takes to hibernate and resume depends partly on how much RAM is present, since it all has to be saved and reloaded. The remainder of the time is going through all the device drivers and asking them to reload their state. Depending on how much ram+hardware you have, and what kind of drivers, this may even take longer than a cold boot.

Can you explain more about what you mean by reduced battery lifetime? If your battery is charged, and the laptop is connected to AC, then it doesn't matter at all whether the laptop is fully running, suspended, or of -- in all cases there is no battery activity, charging or discharging.

You might also be surprised to find how long the laptop can run from battery in suspend mode. Modern CPUs are very good at going to sleep, turning off peripherals, and suspending clocks.

[kaplanfx]

How do I set this sleep to suspend? I can't find any info about it.

Thanks,

-kaplanfx

[skanky]

How do I set this sleep to suspend? I can't find any info about it.

Thanks,

-kaplanfx

i think its in the BIOS, in config/power i think.

[kaplanfx]

Cool thanks, I set it to 90min I'll let you all know how it works out tomorrow.

-kaplanfx

[Navck]

Sorry, I couldn't resist to say this but..
You know what bears do to "hibernate" right? They eat stuff that plugs their digestive track up.
Now how do our laptops "Hibernate", do they plug theirselfs with carbon fiber?

[kaplanfx]

Ok, I set the option in my bios to hibernate if suspended/sleeping for 90mins. Then I booted to XP and slept the laptop for over 2 hours but it did not hibernate. Any idea whats going on here? do I need to set additional options in XP? Does XP's power setting or batt maximizers setting override the bios option? This sounds like a feature that would be useful to me as sometimes I sleep the laptop then fall asleep myself and I'd rather have the laptop hibernate than sleep overnight, esp if the AC adapter is not connected or im away from home.

-kaplanfx

Edit: Do I need to set the Hibernating by timer option in the bios as well? there is no good description of what this does and I don't want to active something that will hibernate my laptop at random (on the timer) times.

[GomJabbar]

All you ever wanted to know about power management, but were afraid to ask - or - why is my battery dead already?

http://informationweek.com/story/IWK20020927S0028

http://www.spcug.org/reviews/vlba0211.htm

http://www.edn.com/article/CA46495.html

http://www.ma.utexas.edu/users/stirling ... aving.html

http://www.apcmag.com/apc/v3.nsf/0/A70E ... enDocument

http://www.microsoft.com/windows2000/te ... by1127.asp

[Inky]

There is one option you haven't considered.. suspend with an automatic hibernation after XX minutes.

So if you originally suspended it, and then left it alone for too long, the laptop can wake up, resume, and immediately hibernate. I think this is an IBM Power Manager feature, not a Windows XP feature.

Cool. I didn't know you could do that.
So, instead of having to decide ahead of time how soon I'll use the ThinkPad again, I could always use Stand-By but anytime I'm not back within, say, 20 minutes, it would automatically switch to Hibernate? That's cool. Thanks Ground Loop!(good name):-)

Also, the time it takes to hibernate and resume depends partly on how much RAM is present, since it all has to be saved and reloaded. The remainder of the time is going through all the device drivers and asking them to reload their state. Depending on how much ram+hardware you have, and what kind of drivers, this may even take longer than a cold boot.

Good point!

Can you explain more about what you mean by reduced battery lifetime? If your battery is charged, and the laptop is connected to AC, then it doesn't matter at all whether the laptop is fully running, suspended, or of -- in all cases there is no battery activity, charging or discharging.

An IBM Tech I spoke with would disagree with that. According to him, even when you're plugged into AC--as long as there's a battery present, the ThinkPad is drawing some current from the battery while the battery is constantly recharging. So keeping the battery present while you're on AC causes some wear on the battery. But that is the price you pay for the benefits of an Uninteruptable Power Supply (protecting any unsaved work from being lost in the event of a power outage or a power cord disconnect).

So, it follows that leaving the ThinkPad on Stand-By whenever it's not in use (all night, etc.) will gradually drain the battery if only a battery is present, or it will cause slight wear on the battery if both battery and AC are present. That's according to the IBM Tech I spoke to.

You know what bears do to "hibernate" right? They eat stuff that plugs their digestive track up.

That's how I hibernate my ThinkPad! I press Fn-F12 then I go eat a giant plate of pasta with a quarter pound of grated Gouda cheese melted on it. Works everytime.


-Inky

[eigh]

bear comments................



when i get my thinkpad, ill ahve to look into the bios power saving thing.

[Rahula]

I have a T23 running on W2K Pro SP4 which I plug into power most of the time. This is my

configuration in the Power Options Properties:

Turn off monitor - 10 minutes
Turn off Hard Disk - 30 min
System Standby - 20 min
system Hibernation - 30 min

After being away from the laptop for 25 min, When I try to wake it from Standby, although

the half-moon LED icon is lit up, it would not wake when I press Fn, or any other key. I

then have to press the power button to put it into hibernation, and then press power again

in order to wake it from hibernation.

I don't know whether something is wrong with the system board, or did I configure it

wrongly. My intent is to minimize wear and tear on the laptop in situations when I don't

know how long I would be away from my work. In the above scenario, should Turning Off HDD

be set at the same time as getting into Hibernation? Would appreciate learning from your

experience and views. thanks.

[GomJabbar]

I have a T23 running on W2K Pro SP4 which I plug into power most of the time. This is my

configuration in the Power Options Properties:

Turn off monitor - 10 minutes
Turn off Hard Disk - 30 min
System Standby - 20 min
system Hibernation - 30 min

After being away from the laptop for 25 min, When I try to wake it from Standby, although

the half-moon LED icon is lit up, it would not wake when I press Fn, or any other key.

Maybe you have done this already, but I have found that sometimes you have to hold the Fn key down for a few seconds to come out of standby. Occasionally I have had to press the Fn key 2 or 3 times to come out of standby. This was on a 600E.

If the above doesn't work, check the BIOS settings in the T23. You may have to choose a different power save mode for standby to work. I had to do this on a P4 desktop system.

[asiafish]

There is nothing wrong with your system board. You are simply experiencing the instability and lack of reliability of Standbye under Windows. Just kill standbye in your PM settings and use Hibernate all of the time instead.

[GomJabbar]

asiafish and I, have batted this around before. Some have had difficulties (like asiafish), and some use it all the time like myself. I used standby in the past on my 600E running W2K and now on my T42 running XP Pro. I have had no reliability problems with standby as long as I don't unplug any hardware while the system is in standby.

[Rahula]

The problem is, when it wakes from hibernation, I have to enter the password. Is there any way to disable this password requirement when waking from hibernation? Couldn't find this disabling feature in W2k.

Also, someone earlier in this thread distinguish Power Management in Access IBM vis-a-vis Windows but, to me, they both seem to lead to the same page: Power Options Properties.

[GomJabbar]

The problem is, when it wakes from hibernation, I have to enter the password. Is there any way to disable this password requirement when waking from hibernation? Couldn't find this disabling feature in W2k.

I don't have a W2K system handy, but see if the following will work for you. Right click on an open area of the desktop, choose: Properties > Screen Saver > Power... > Advanced > uncheck box for: 'Prompt for password when computer resumes from standby'.

[Rahula]

GomJabbar - thanks, it works.

[bvaughn]

So, I use STAND-BY only for brief interuptions. Overnight I always use HIBERNATION.

Perhaps I've missed something too obvious for cognoscenti to mention, but I wonder: Why would anyone leave a ThinkPad turned on overnight? I always turn off both of my computers at the end of the workday. I usually turn them off if I go away from the desk for more than an hour. Enlighten, please.

[GomJabbar]

Perhaps I've missed something too obvious for cognoscenti to mention, but I wonder: Why would anyone leave a ThinkPad turned on overnight? I always turn off both of my computers at the end of the workday. I usually turn them off if I go away from the desk for more than an hour. Enlighten, please.

Because we are an impatient lot. It's less of an issue with the newer computers, but it's the boot-up time that we are eliminating. With my previous PII laptop and Norton AV installed, it took close to 5 minutes to fully boot up. My new laptop boots up in roughly a minute. Whether it's 1 minute or 5 minutes, that's time wasted while we are waiting for the computer to be ready to use. When we grab our laptop that's been on standby or in hibernation, within seconds we are using it.

It's analogous to the 'instant on feature' that modern picture tube (CRT) televisions have. On the TV the picture tube has an element that has to be red hot before the tube will show a picture. With the 'instant on feature', this element is kept hot all the time, but everything else has no power. When you turn the set on, you don't have to wait for this element to heat up, so you can see a picture much quicker this way.

[Inky]

So, I use STAND-BY only for brief interuptions. Overnight I always use HIBERNATION.

Perhaps I've missed something too obvious for cognoscenti to mention, but I wonder: Why would anyone leave a ThinkPad turned on overnight? I always turn off both of my computers at the end of the workday. I usually turn them off if I go away from the desk for more than an hour. Enlighten, please.

I also turn my desktop computer off at the end of the day. But I got the ThinkPad specifically for creative writing (books and screenplays) and some of my best ideas come to me when I'm lying in bed. At those times I reach over and grab my ThinkPad and having it in hibernation means I'll be in my document in moments.

When a new creative thought appears in your mind, it is in a delicate state and easily evaporates if suddenly confronted with distractions like a long Windows boot sequence. At those times quick bootup really matters.

Remember though, that HIBERNATION doesn't mean the computer is somehow on. It is just as switched OFF as if you had done a regular shut down. You ARE shutting down, but in a way that creates a hibernation file so you'll be able to resume where you left off. It's merely a bookmarker.

-Inky

[GeorgeP]

Perhaps I've missed something too obvious for cognoscenti to mention, but I wonder: Why would anyone leave a ThinkPad turned on overnight? I always turn off both of my computers at the end of the workday. I usually turn them off if I go away from the desk for more than an hour. Enlighten, please.

I rarely turn mine off, maybe once a week. Instead I always put it in standby mode when I'm finished, even overnight. This saves lots of time because when I resume from standby, there is no boot up time and I'm right back where I left off.

Actually, I don't see why one would turn their machine off when you can suspend.

G

[Inky]

Actually, I don't see why one would turn their machine off when you can suspend.
G

Windows has always been prone to a gradual corruption of the RAM contents when it is running for long periods without rebooting.

Since StandBy keeps the RAM contents as-is (and Hibernation RESTORES them as-is) it's a good idea to do a full reboot every once in a while just to refresh the RAM contents.

-Inky

[GeorgeP]

Windows has always been prone to a gradual corruption of the RAM contents when it is running for long periods without rebooting.

I think most of the problem is due to resources not being properly deallocated and reused...memory leaks for example. With the software I run, I find rebooting once a week is sufficient for cleaning up problems. XP SP2 seems better in this regard than earlier versions of Windows.

G

[beerak]

Windows has always been prone to a gradual corruption of the RAM contents when it is running for long periods without rebooting.

I think most of the problem is due to resources not being properly deallocated and reused...memory leaks for example. With the software I run, I find rebooting once a week is sufficient for cleaning up problems. XP SP2 seems better in this regard than earlier versions of Windows.

G

yes, I need to do the same, once a week I restart system. It clears machine and then I use hybernation for a week again

[JHEM]

I think most of the problem is due to resources not being properly deallocated and reused...memory leaks for example. With the software I run, I find rebooting once a week is sufficient for cleaning up problems. XP SP2 seems better in this regard than earlier versions of Windows.

But still not perfect.

My machines normally travel suspended and I rarely hibernate any of them.

As my running time progresses I'll notice a slowdown in many processes, therefore about once a week or so I'll reboot my daily driver to "refresh" everything. Makes a noticeable difference.

Regards,

James

[Inky]

Sounds like we're all in agreement then.
Once a week = once in a while.
Like I said, it's a good idea to do a full reboot every once in a while just to refresh the RAM contents.

And whether you prefer using Hibernation or StandBy, in either case the RAM contents are not getting refreshed. That's why those of you who use Hibernation and those of you who prefer StandBy are all noticing benefits from rebooting once a week.

-Inky