So, should you leave your Mac on while you're at work, or asleep, or asleep at work?

First, the pros. Here's why you should leave it on, especially at night. Back in the day when Unix boxes were the size of rooms and not everyone had a computer, Unix used what are called cron jobs to "clean up." Those cron jobs run in the middle of the night when most folks were not using the computer.

Your Mac is now Unix-based, and those cron jobs still run in the middle of the night. The cron jobs are important to keeping your Mac running smoothly.

So you should leave your Mac on so the cron jobs run.

There are other reasons to leave the machine on. And here's where some of the debate begins. Some say that it's not the day-to-day use of the moving parts, meaning the hard drive especially, but the starting and stopping.

It also, to a point, doesn't hurt your Mac to have a bunch of programs running. Again referencing Unix, the Mac "pages" unused programs, while still open, to the hard drive, where the OS can get it back quickly if you begin to use the program again.

And finally, do you really want to wait for the computer to start up?

Now for the other side.

There are many utilities that will run the cron jobs any time you want them run. Or you can even use the command line to edit the cron jobs and change when you want them to run. So there's no reason to leave the machine on just for the crons.

As far as the wear and tear on the equipment, others say that keeping the hard drive spinning just gets you closer and closer to the day it will fail. And that is not a typo or a misprint. Your hard drive will fail. At least twice in this space have I written about backups. Do them. Before the drive fails and you lose everything.

Some folks also say that if the computer is on during a thunderstorm, you're more likely to get zapped. I'm not so sure of that, in fact, if the thing is plugged in, you can still get zapped if your surge protector fails (and some would argue that most of them do anyway).

Those are the arguments. Here are my experiences and recommendations as a Mac tech at a newspaper for more than a decade. Your mileage may vary.

At home, I never turn my computers off. They run night and day. I set the hard drives to never spin down. The displays shut off after about 30 minutes, but the machines continue to run.

My Powerbooks are also always on. When I can, they are plugged in, except the old G4/550 PowerBook,whose battery is toast and must stay plugged in. The PowerBooks are, of course, put into sleep mode when the cover closes.

At work, it's a different story. There, most of the Macs are powered down at night. Of course, servers, which are designed to run constantly, run continuously. Most of my Macs at work have shown now ill effects of being turned on and off each day. They run OS 8.6 and 9 (upgrades are coming in the next few weeks) and we put out the paper each day with them.

So, what should you do? Do what you want. I don't have any of the newer iMacs with the tiny cases. I don't have any minis. But aside from some faulty components causing some problems, I haven't heard bad things about those machines.

Now, play nice in the comments, boys and girls.