Leaving Mac On -- Advantages / Disadvantages
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From: Davoud on 16 Feb 2010 22:03 Nick Naym: > There seems to be two schools of thought: One, which takes the position that > leaving the machine on 24X7 shortens its life due to the wear & tear of > constant operation; the other, which believes that the wear & tear of > constant operation is minimal compared to the cumulative stress caused by > repeated, daily powering up and shutting down. Bzzzzzt! The "stress" caused to a piece of electronic gear by turning it on and off is pure myth. Study after study, some published and some not, and tons of empirical evidence support that. > I've always tended to agree > with the latter (ever notice that light bulbs tend to fail more often during > the electrical surge that occurs when you flip the switch, rather that while > they're running constantly in steady state?). Bzzzzzt! There is no surge when you turn a switch on. The voltage goes from 0 to 117V almost instantaneously; a "surge" implies that the voltage overshoots the 117V and then settles back to 117V. There is no mechanism (such as a capacitor circuit) in a light switch that can cause such a "surge." If a light bulb fails upon initial application of current it is because of the sudden heating of a filament that is either defective or, more likely, old and about to fail anyway after a few more hours of use. > The optimum likely is somewhere in between, depending on how often you turn > the machine on & off. Everyone has their own prescription, and mine is to > leave the machine running (with scheduled sleep periods every night) unless > I expect not to be using it for an entire day or more. As I said earlier, I am not criticizing your way. But from the viewpoint of saving energy, only a night-time shutdown makes sense. Do you leave all the incandescent bulbs in your home turned on 24/7 in order to avoid the stress to the filament from sudden heating? Stove? Oven? Washer and dryer? Dishwasher? Hot water running constantly? If it doesn't make sense to you to do that, you might want to consider why you think your computer is in a special category and needs to run 24/7. Davoud -- I agree with almost everything that you have said and almost everything that you will say in your entire life. usenet *at* davidillig dawt cawm
From: TaliesinSoft on 16 Feb 2010 23:51 On 2010-02-16 16:51:31 -0600, Richard Maine said: > There are climates where heat pumps don't work well... Hmm, I see you > have a .ca address, so you might be in one of those climate zones, but > don't overgeneralize. In climates where they work, heat pumps are far > more efficient ways of heating electrically than resistive electric > heaters... or using waste heat from computers. I lived in southern New Jersey for quite a few years in a house that was heated and cooled with a water exchange system that used water from a deep well. The temperature of the water year round varied only slightly from fifty-five degrees, meaning that in winter the water was warmer than the outside temperature and in summer it was cooler. The result was that my heating and cooling bills were significantly lower than that of my neighbors. -- James Leo Ryan --- Austin, Texas --- taliesinsoft(a)me.com
From: Kevin McMurtrie on 17 Feb 2010 00:24 In article <7tvontF194U1(a)mid.individual.net>, TaliesinSoft <taliesinsoft(a)me.com> wrote: > Except when I have my MacBook Pro away from home I leave it > continuously on, having the display go to sleep after five minutes of > inactivity. Leaving it on during the night is so that the nightly > maintenance routines and my scheduled backups will run. What I'd be > interested in knowing is what disadvantages are there to leaving my > computer on in this manner. Maintenance tasks not running was solved. Some may argue that powering it on and off will cause thermal stress. It's not entirely a valid argument because a modern computer will change temperature with system load variations anyway. While hard drives do have a limited number of spinup and spindown cycles in their life, laptop drives are usually replaced because of head crashes or obsolescence. Dirt accumulation is worse with a continuously running system. Cleaning out a laptop is NOT fun. Putting the system to sleep or shutting it down saves power. -- I won't see Google Groups replies because I must filter them as spam
From: thepixelfreak on 17 Feb 2010 01:12 On 2010-02-16 19:03:15 -0800, Davoud <star(a)sky.net> said: > Nick Naym: >> There seems to be two schools of thought: One, which takes the position that >> leaving the machine on 24X7 shortens its life due to the wear & tear of >> constant operation; the other, which believes that the wear & tear of >> constant operation is minimal compared to the cumulative stress caused by >> repeated, daily powering up and shutting down. > > Bzzzzzt! The "stress" caused to a piece of electronic gear by turning > it on and off is pure myth. Study after study, some published and some > not, and tons of empirical evidence support that. Bzzzzzzzzt! I've worked for a Supercomputer manufacturer for the past 15 years and a total of 20 in the computer industry. I _routinely_ see plenty of real world evidence to the contrary. The machines we make have many thousands (8192 cores currently) and many many Terabytes of memory and Petabytes to Exabytes of attached rotational disk media. I am also a professional member of the ACM (Association of Computing Machinery) and have read numerous articles suggesting what you do. These articles DO NOT agree with my experience. Many of the studies (not all) you posit deal with statistically insignificant numbers of components. The very large component count machines we make (whether they be large NUMA SMP machines or large cluster supercomputers) exhibit statistically significant component failure after power has been removed for significant periods of time. These effect tend to manifest themselves more in rotational media than integrated circuits but nonetheless I see it in all components. That said, untoward effects of the power cycle on desktop computers with relatively very few components these days is likely to be rather minimal. -- thepixelfreak
From: Nick Naym on 17 Feb 2010 03:11
In article 160220102203159807%star(a)sky.net, Davoud at star(a)sky.net wrote on 2/16/10 10:03 PM: > Nick Naym: >> There seems to be two schools of thought: One, which takes the position that >> leaving the machine on 24X7 shortens its life due to the wear & tear of >> constant operation; the other, which believes that the wear & tear of >> constant operation is minimal compared to the cumulative stress caused by >> repeated, daily powering up and shutting down. > > Bzzzzzt! The "stress" caused to a piece of electronic gear by turning > it on and off is pure myth. Study after study, some published and some > not, and tons of empirical evidence support that. > >> I've always tended to agree >> with the latter (ever notice that light bulbs tend to fail more often during >> the electrical surge that occurs when you flip the switch, rather that while >> they're running constantly in steady state?). > > Bzzzzzt! There is no surge when you turn a switch on. The voltage goes > from 0 to 117V almost instantaneously; a "surge" implies that the > voltage overshoots the 117V and then settles back to 117V. There is no > mechanism (such as a capacitor circuit) in a light switch that can > cause such a "surge." If a light bulb fails upon initial application of > current it is because of the sudden heating of a filament that is > either defective or, more likely, old and about to fail anyway after a > few more hours of use. > There is always a slight amount of capacitance and inductance inherent in the circuit, so a slight amount of underdamping can be expected. However, the biggest contributor to the surge is related to what you yourself mentioned: sudden heating. Specifically, the resistance of a "cold" circuit is less than that of a "hot" circuit, so when the switch is initially closed, the applied voltage "sees" a smaller resistance that it does later on after the filament has heated up. Consequently, the initial current is higher than its steady-state value. IOW, the surge that causes the bulb to fail is a current surge, and not a voltage surge. >> The optimum likely is somewhere in between, depending on how often you turn >> the machine on & off. Everyone has their own prescription, and mine is to >> leave the machine running (with scheduled sleep periods every night) unless >> I expect not to be using it for an entire day or more. > > As I said earlier, I am not criticizing your way. But from the > viewpoint of saving energy, only a night-time shutdown makes sense. Energy savings is not the issue. > Do > you leave all the incandescent bulbs in your home turned on 24/7 in > order to avoid the stress to the filament from sudden heating? No. But I don't worry about them...I turn them on or off depending on my needs. And when they fail, I replace them (increasingly, BTW, with CFLs). But my relationship with light bulbs is not the same as my relationship with my Mac: I am much more concerned about the potential harmful effects of the shock of turning the power on/off on my $1,800.00 iMac than I am on a few $0.50 light bulbs. > Stove? > Oven? Washer and dryer? Dishwasher? Electrically, they're not in the same category as a desktop computer. > Hot water running constantly? I think you're injecting the energy issue again. > If it > doesn't make sense to you to do that, you might want to consider why > you think your computer is in a special category and needs to run 24/7. > Because it _is_ in a special category. Whether letting it run pretty much 24X7 actually extends its expected life is anyone's guess. I've opted to do it this time around for the reason I indicated; I may decide otherwise the next time around. -- iMac (24", 2.8 GHz Intel Core 2 Duo, 2GB RAM, 320 GB HDD) � OS X (10.5.8) |