This is a hottly debated subject heer on the forums. The answer is what ever works best for you is what you should do. I personally always sleep mine. I do this because I like to have the websites and pages up on my machine when the machine comes back up the next day. I dont think I have ever turned my iMac G5 off for more than a few minutes. I have had to restart it a few times to fix hanging programs and the like, but I don't think it really matters.
I should say, if you have one of the early imac G5's rev A or B maybe turning the machine off would be best. The heat those machines can put off for some owners might degrade the machine faster than a cooler running rev C or Intel model. But, that's not scientific or fact, just my opinion.
In the end, whatever works for you is the answer. I think Macs are made to run 24-7 and I personally know people with machines that have been running for years with no problems. In fact the OS is designed to take advantage of a machine that is always on. The maintenance programs built-in to Mac OSX run during those quiet times of the day when the machine isnt being used. So it may very well be, best to leave them on so that stuff gets done.
Good luck, hope that helped you.
The most demanding task for a computer most probably is a cold boot (a simple restart, with all components already warm, is not so "harmful").
Certainly sleep causes less wear and tear, but it is not such a huge difference, that it should influence your habits and your energy saving concerns.
I guess your computer will be already obsolete since a long time, before you can clearly measure some damage that would have been caused by too many cold boots.
Macs are designed to be left on 24/7, but they are also very well designed to cope with different kinds of users habits.
Nightly automatic maintenance:
This neither is a good enough reason to influence your sleep vs shutdown habits.
Simply run the three "daily", "weekly" and "monthly" tasks yourself manually, twice a month or so, with Cocktail, TinkerTool System or such an utility.
Sleep versus Shutdown: A matter of personal preference really.
Like DF/W I vary things a bit.
Firstly, it actually depends on what software you run regularly to some extent.
While programs are all MEANT to let go memory elegantly these days, not all of them do. If you find that your Mac is starting to slow up, and things aren't behaving quite as they should a restart is the first thing to try.
I find a shut down and "cold" startup (not just a "restart"), is not a bad idea every few days.
AS far as wear and tear goes, there are arguments both ways, but anyone who had one of the old "Summer 2000" iMac G3's (like me!) will tell you that at least on some drives , and if you have any sleep problems at all preventing the computer from sleeping "deeply", then bearing wear on HD's , resulting in annoying noise, can become an issue if they are left running continuously.
Its worth noting that these days the "sleep" process actually drops off power usage to pretty low levels, so some of the old arguments about leaving things running to avoid significant power and thermal "shock" to the system probably don't really apply any more. The change in such things when moving from deep sleep to full operation really isn't that different between the two approaches any more.
Regardless of whether you sleep or shut down your iMac at night, remember that the regular automated Unix "housekeeping" tasks won't be getting run unless the Mac is up and running, so use something like "MacJanitor" or "Onyx" every week or so to do so instead.
Have a look at the explanation at http://personalpages.tds.net/~brian_hill/macjanitor.html
On a Mac which is running continuously the daily script runs at 3:15 a.m.; the weekly, at 4:15 a.m. on Saturday; and the monthly, on the first day of each month at 5:30 a.m.
There is not really any need to run them quite so often, but I usually simply run MacJanitor every week or so to make sure things don't get out of hand.
If the tasks are run reasonably regularly then they don't take all that long (the weekly is the slowest). If you leave your Mac running overnight (not sleeping) on Friday nights, and on the night beginning on te last day of the month, you will be getting them all often enough.
You can also reschedule the tasks if you want them to run at a different, more convenient time. see http://www.macworld.com/2003/12/secrets/handson/index.php/ for an excellent explanation. CronniX is a useful utility for doing this.
But I personally find simply running MacJanitor every week or two works fine for me.
I know nothing about the regular automated Unix "housekeeping" tasks.
How often do you recommend that I leave my iMac to sleep at night rather than be shut down?
The housekeeping tasks will not run if the iMac is asleep.
Also, you can set the Energy Saver -> Options - Schedule to start up and shut down the computer automatically.
There are also progs to turn it on/off & run scripts all kinds of different ways.
Ellwin, you have asked the second most divisive question on these discussion boards. After we settle this for you, I dare you to post about anti-virus software - LOL!
Anyway, today's computers are pretty much designed to remain on 24/7/365, but that does not mean you have to leave it on all the time. There used to be issues with sleep that prevented the daily/weekly/monthly maintenance tasks from running, but that was finally resolved with the release of Tiger 10.4.3 - which you are running. Now if you choose to sleep your Mac, the tasks that would have been run when your Mac was sleeping will be run when it is awakened.
I leave mine on - no sleep, just the monitor off after 15 minutes - and have had no problems at all. I have read in many places that the toughest time on your computer is the heat cycling caused by turning the computer on and off. That is why I leave my Mac and my PC on all the time.
That said, there are some precautions that need to be taken. Skip a surge protector and go right for a good quality UPS battery backup. This serves as a surge protector and also powers your Mac in case of a power failure. Tiger should recognize the UPS so it can be set to automatically shut itself down the correct way - saving the system files from corruption and preventing the hard drive from suffering physical damage from the arms crashing into the platters which could render your data and the drive useless.
If you want to use a tool like Cocktail to force scripts, go ahead, but I only use it when there is an OS update out there to be applied. Since I do not sleep my Mac, the tasks get run as scheduled overnight.
I am an uptime junkie. It really serves no purpose, but I take delight in the fact the the only time I reboot my system is when I am forced to be a system update. Right now, I am at 36 days since the 10.4.6 update. If I have a (rare) problem, logging out and then logging back in solves it for me.
Some programs can be memory hogs, Safari in particular. I use Camino as my browser and have never had a problem reading sites or with the creeping CPU and memory use that comes with Safari use. I also leave all my regularly used apps open all the time - Camino, NewsFire (RSS reader), iTunes, and Temperature Monitor. The other apps that I use, like Dreamweaver and Photoshop get opened and closed all the time.
This is what works for me and is by no means meant to be definitive for everyone. Bottom line is do what works for yoou. Neither one is really any better or worse than the other, but avoid cold starts if possible. Get a UPS - APC brand if possible.
There used to be issues with sleep that prevented the daily/weekly/monthly maintenance tasks from running, but that was finally resolved with the release of Tiger 10.4.3 - which you are running. Now if you choose to sleep your Mac, the tasks that would have been run when your Mac was sleeping will be run when it is awakened.
Well, what do you know, Eric. You are dead right! I just checked my logs, and there we are! Log files being rotated, locate databases being rebuilt, you name it! All on the first wake up after the appropriate scheduled time (as well as whenever running MacJanitor has taken my fancy)!
As you say, it seems to have been going on like this since the time I installed 10.4.3 too!
Apologies Klaus and others. I should have known that this had been fixed.
Many thanks Eric. Looks like MacJanitor can head off to retirement (I've been using it for years).