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Running your Mac 24/7 vs. shutting down at night

S

SteveC

macrumors 6502
Original poster
Jul 7, 2003
438
0
Hey everyone... A friend told me today that shutting your computer off at night is a bad idea. He said it should be left on 24/7, citing two reasons:

1. Macs perform directory maintenance during the night, after a few hours of inactivity. What does directory maintenance do and how long does it take? Can it be initiated manually, or will it only happen by leaving it on at night?

2. It produces more strain on the hardware during startup. He said the most stressful time for the hardware is on boot-up.

It made me wonder though, isn't leaving on for 8 hours going to be more "hardware usage" than a 1 minute startup? I could be wrong, but it sounded really odd to me. 😉
 
I leave my Power Mac and my iBook running 24/7, and I have had zero problems. I've found that it seems to be less stressful on the systems when they are left running, rather than sleeping and waking every few hours.

Daniel
 
For one thing, are you really using your computer for the other 16 hours of the day, or putting it to sleep, which is exactly the same as shutting it down from a hardware wear perspective?

Your friend is right about the maintenance scripts, so as the previous poster said you should probably run them manually once in a while (via the terminal or any of a variety of GUI tools). Personally, I'm awake and working on my computer at 4:30am frequently enough that I don't need to bother.

Your friend is likely wrong about the startup stress, though. There are heat expansion/contraction issues that COULD affect some hot parts (the processor), but that's highly unlikely to make any noticable difference in lifespan. The fans probably don't much like startup, either, but just being on wears the bearings too, so I doubt that matters.

The only part that on-off cycles might actually affect is the hard drive... but that doesn't matter either, since OSX probably puts the drive to sleep (which is the same as turning the whole machine off from its standpoint) on inactivity anyway. Even then, I'm not sure that 8 hours of constant use would make the drive last longer than a "rest" period and a short spinup every night--after all, modern OSes sleep the drive all the time and if anything lifespan has gone up (warranties have, anyway), so I assume they're built to take this.

Don't forget also that you're using a lot of electricity leaving the computer on at night. Pure waste issues aside, if you have (for example) a G5 tower, 8 hrs X 170W (idle) = 1.4KWh/day = 500KWh/year. At what I pay for electricity, that's $80 a year, so even if you are wearing your hard drive out a bit faster you'll pay for a new drive in two years of shutting down at night.

Not a big difference, but worth noting that some Apple machines use more power when asleep than shut down (the G5 towers are 10W vs 2W), while others are nearly identical so it doesn't matter.
 
I almost always run my Powerbook 24/7, with a few sleeps in between when I take it out, but when its home, its almost always turned on. I turn the display off when I go to sleep.

my friend has a G4 MDD, and has had it for 2 years now... I dont think hes ever turned the thing off, lol, and its still working great.
 
This is some truth to the idea that you should leave your computer on all the time. For example, it puts more stress on the hard drive to start/stop than to just let it spin. On the other hand, yes, equipment can also wear down if it's constantly running.

AFAIK, there's no conclusive evidence that you should do one or the other. Personally, I leave my computers running 24/7 unless I know I'll be away for a few days or something like that.
 
I leave my computer on 24/7, only having my display go "off" after 15 minutes of inactivity. Not for any preservation reasons, but because I don't want to go offline - I have iChat up 24/7 so people can leave messages when I'm not around.

(I put " "'s around off because my display doesn't actually go off, the graphics card just stops giving it a signal, so the screen just goes black.)
 
Makosuke said:
For one thing, are you really using your computer for the other 16 hours of the day, or putting it to sleep, which is exactly the same as shutting it down from a hardware wear perspective?

Your friend is right about the maintenance scripts, so as the previous poster said you should probably run them manually once in a while (via the terminal or any of a variety of GUI tools). Personally, I'm awake and working on my computer at 4:30am frequently enough that I don't need to bother.

Your friend is likely wrong about the startup stress, though. There are heat expansion/contraction issues that COULD affect some hot parts (the processor), but that's highly unlikely to make any noticable difference in lifespan. The fans probably don't much like startup, either, but just being on wears the bearings too, so I doubt that matters.

The only part that on-off cycles might actually affect is the hard drive... but that doesn't matter either, since OSX probably puts the drive to sleep (which is the same as turning the whole machine off from its standpoint) on inactivity anyway. Even then, I'm not sure that 8 hours of constant use would make the drive last longer than a "rest" period and a short spinup every night--after all, modern OSes sleep the drive all the time and if anything lifespan has gone up (warranties have, anyway), so I assume they're built to take this.

Don't forget also that you're using a lot of electricity leaving the computer on at night. Pure waste issues aside, if you have (for example) a G5 tower, 8 hrs X 170W (idle) = 1.4KWh/day = 500KWh/year. At what I pay for electricity, that's $80 a year, so even if you are wearing your hard drive out a bit faster you'll pay for a new drive in two years of shutting down at night.

Not a big difference, but worth noting that some Apple machines use more power when asleep than shut down (the G5 towers are 10W vs 2W), while others are nearly identical so it doesn't matter.
Click to expand...
Aren't you making some assumptions as to his Energy Saver settings? I know my disk drive doesn't sleep when idle.

Anyway, as a data point, my TiBook has been running pretty much 24x7 for 18 months, because I Fold ( there's a MR Forum, if you're interested). It sleeps only when traveling. No problems, although the fan runs 100%.

In the old days, startup and shutdown stress was a consideration. Modern electronics don't seem to be as sensitive to that, but again, all my machines (4) Fold 24x7, so they're never off, but they're not wasting cycles, either (they're doing protein related medical research). In my mind, it's the best all round, as long as you're doing something useful.

BTW Makosuke, no system uses anything close to its average power consumption when it's idle.
 
Very helpful responses so far. 🙂 Thought I'm NOT surprised. 😉 MR is an awesome place to learn and share information, and I fully expected great replies like the ones above.

All this input helps me understand the pros and cons of doing it one way or another.

I guess it just seems hard for most people to believe that starting up the computer is more intense than running the computer for 8 hours. I'm just picturing the hard drive spinning for 8 hours and the fan spinning and thinking it would prolong the life to shut if off.

I wish we had some solid info. on this. 😛 Although, I really do guess it *doesn't matter*... lol.

The computer would probably last 5 years without blinking if you ran it 24/7, and it would probably last 5 years if you turned it off at night and back on in the morning. I guess the small differences caused by "wear and tear" are so small that you'd want to upgrade your computer before it would get close to dying anyway............................ Seem logical?
 
auxplage said:
There are maintenance scripts that are done every night at 3 AM or something, so one must do them manually if there computer is asleep or shutdown. I put my computer to sleep always (like most Mac users I think), so I use this http://www.versiontracker.com/dyn/moreinfo/macosx/10491 to run them. One can also run them throught the terminal, but I am too lazy.
Click to expand...
Thanks for the link, by the way. 🙂 Does the program "Onyx" do the same, or a similar, thing? What's the best one to use?
 
The main reason I don't like to leave my eMac running all the time is because the fans run constantly...which will make the bearing wear out quicker. I prefer to put it to sleep, but it always seems to screw up my iPod when it wakes up (iPod says "Do Not Disconnect" but it doesn't even show up in Disc Utility so I can eject it).
 
Your computer's not really any different from other appliances that you never switch off - when did you last turn off your fridge? My G4 tower only gets turned off for transportation or internal tinkering 😉
 
What about a PeeCee running 24/7 without restarting? (if you can make it that long without having to) ROFL 😛
 
So does that mean restarting has a similar effect on hardware? 😕

I've always been afraid my hard drive would fizzle on me if I left the computer on all night, although what everyone says makes sense...
 
I shut mine down every night. I keep thinkning that it saves me some $$ on my electricity bill, but I'm sure it's a miniscule amount.
 
I'm wondering... how long does the battery last (until it needs replacing) on powerbooks/ibooks running 24/7? I mean it's being used/recharged constantly that way, now that's gotta shorten its lifespan.
 
My Powermac G5 has been on most of the time since October of 2003. I had problems when I turned it off or had it go to sleep because of the video card wouldn't come back to life. I replaced the video card and now it works fine. But I am so use to have it on all the time that it doesn't bother me anymore. I have 2 internal HDs and a 6800 generating lots of heat. I video encode freqently over night so it gets a workout. The case, fans, and cooling engineering seemed to have paid off. I hope I can squeeze another 4 more years out of it before my next Powermac purchase.

I let my hard drives sleep so I get a longer life from them. I suppose I should let my G5 sleep if I am not using it.
 
diff said:
I'm wondering... how long does the battery last (until it needs replacing) on powerbooks/ibooks running 24/7? I mean it's being used/recharged constantly that way, now that's gotta shorten its lifespan.
Click to expand...

If you have a PB normally standing at home should you leave it in the charger or should you let it discharge 😕
 
So is it a good idea or a bad idea to check "Put the hard disk(s) to sleep when possible" in the system prefs? I'm on an iMac, so I don't have power issues. I just always though it was best to have it spun down wheneve possible.
 
VAmin said:
So is it a good idea or a bad idea to check "Put the hard disk(s) to sleep when possible" in the system prefs? I'm on an iMac, so I don't have power issues. I just always though it was best to have it spun down wheneve possible.
Click to expand...
if you don't mind the minor amount of noise, I think it's preferable to let them spin.
 
SteveC said:
Hey everyone... A friend told me today that shutting your computer off at night is a bad idea. He said it should be left on 24/7, citing two reasons:

1. Macs perform directory maintenance during the night, after a few hours of inactivity. What does directory maintenance do and how long does it take? Can it be initiated manually, or will it only happen by leaving it on at night?

2. It produces more strain on the hardware during startup. He said the most stressful time for the hardware is on boot-up.

It made me wonder though, isn't leaving on for 8 hours going to be more "hardware usage" than a 1 minute startup? I could be wrong, but it sounded really odd to me. 😉
Click to expand...
The Mac is designed and intended to be left on 24/7. If this were not the case, Apple would have included a script to execute the cron maintenance tasks at a time of the user's choosing. As a general rule, electronics don't like being switched on and off. Thermal cycling generates cracks in conductive traces and soldered connections. Traditionally, the switches themselves are among the most failure-prone parts. However, I would think that Energy Star requirements mitigate the benefits as well as the expense of leaving the computer on. Apple substantially mitigates the danger switch failure by using capacitive proximity switches rather than mechanical ones. Having a computer on 24/7 mandates safe reliable electric power. My community has highly unreliable, badly conditioned power. I use a UPS to condition my power and as insurance against power outages. You should use a UPS anyway, but you really need it if your leave your computer on 24/7.

In the end, I come down on both sides of the debate. Under ideal conditions, it is better to leave the computer on. Under less than ideal conditions, it depends.
 
I wonder how much money you save by sleeping a machine at night? I had a G5, G4 & G3 all running at night, and my electricity bill went up a lot for a month. Now I usually just sleep my G5 and wake it in the morning.


Funny thing: OS X still records up times even when it sleeps. For example, 12 hours awake + 12 hours sleep = 24 hours uptime. Linux will only count that as being awake for 12 hours.
 
There are exceptions to leaving it on 24/7. Such as during electrical storms or rolling blackouts or brownouts. If you leave it on 24/7, you should look at getting a UPS or a surge protector.
 
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