This story starts back in July, when Geoff and I installed a Power Macintosh 7100/66 in the offices of Point of Presence Company, where our main Web and mail server (an Apple Workgroup Server 6150) also lives. The 7100 was destined to run StarNine's ListSTAR and handle the entire TidBITS mailing list - and it's done swimmingly well at that task.
But that's not the mystery.
The 7100, as you probably know, is a "soft-power" Mac - you turn it on from the keyboard and off with Shut Down from the Special menu. Our other server is a "hard-power" Mac that has a constant power switch, meaning that once the power switch is on, it stays on. These facts are important for servers, because if the power goes out and stays out longer than an uninterruptible power supply can withstand, the servers will shut off. The question is, what happens when the power comes back on?
The AWS 6150, being a hard-power Mac, comes back on automatically. The 7100, on the other hand, is a bit of a problem, because it uses a momentary power switch: simply restoring electricity doesn't automatically turn the machine back on. So how do you get it to restart after the power comes back on?
Way back when soft-power Macs first appeared, Apple realized this was a problem and solved it in an ingenious way. All soft-power Macs have a reset switch (originally in the back, although it's on the front of newer Macs). On older Macs with the rear-mounted reset switch (including the IIci and the 7100) the switch is notched, like a screw. To ensure that the Mac restarts when power returns, you used a screwdriver to turn the switch and press it in. Clean and simple, if not inherently obvious.
After setting everything else up, Geoff and I tried to lock the reset switch in, to ensure the 7100 would recover from a power outage. The only problem was that it wouldn't lock. We shut the machine down, disconnected all the cables, pulled it off its rack, and opened it up. Lo and behold, there was no catch inside the case for the switch to latch into.
Being slightly more clever than your average wombat, we realized we could hold the power switch in using a piece of a paper clip to hold the power switch in. So, we put the case back on, stuffed it back on the rack, reconnected all the cables, and pushed the keyboard's power key. Nothing. With the switch in that far, the 7100 wouldn't even start up.
Out with the cables, down from the rack, off with the case, and we removed our handiwork. We were completely stumped, and saw nothing to do but put it all back together normally and hope the power didn't go out for too long.
Fast forward to Macworld Expo in Boston. Apple Tech Support had a booth there, so I stopped in and asked about this problem. The guys there, although they sounded like they knew what they were talking about, hadn't a clue what to do. I left feeling a little better that we'd been stumped before.
Then, just a few days ago, the revelation came. I was poking around Maxum's Web site for information about PageSentry 2.0, their new monitoring tool for Internet servers (which is quite cool), when I ran across a tech support posting noting that since the Quadra 840AV, the switch no longer locks on soft-power Macs.
Instead, it turns out, the trick is to use the Energy Saver control panel. If you open the control panel and choose Server Settings from the Preferences menu, you get a dialog that offers a checkbox for "Automatically restart after a power failure."
To be fair, I haven't tried this yet on our 7100, since I'm leery of installing things remotely, and the Energy Saver control panel wasn't on that Mac - we probably threw it out since we didn't think it was necessary for a headless server. But, the next time I visit the server in person, I intend to install a copy of Energy Saver, just in case.
In addition, since I haven't yet visited the 7100 since I learned this fact, I'm not entirely sure how it interacts with the PowerKey Pro from Sophisticated Circuits, an essential little device that (among many other things) can restart crashed servers automatically. It's definitely worth testing if you find yourself in this situation, and one of these months I'll make it into Seattle to visit the 7100, at which point I'll be able to test this in person.
If you're a developer writing server software, however, you don't have to be a slave to a machine's power switch. For many Macs, it's possible to write code to configure a machine to restart automatically after a power failure, in much the same way as the Energy Saver control panel.