I have a loaner MacBook for an upcoming project. It’s a gradual move-in process. First I run Software Update, and then I start installing the apps I need. Inevitably, a few weeks’ worth of music and movies go into the iTunes library and some useful Automator workflows are copied and installed as plug-ins.
On and on. There’s one last thing that I might not get to right away, but always happens…and usually after a lot of cursing.
I go into Terminal and type
sudo pmset -a lidwake 0
…and then I enter my admin password. This disables the MacBook’s “Wake from sleep when lid is opened” behavior.
“Why the bloody hell would _anybody_ want to disable that?” you might ask. “What, you often open your MacBook just to check your makeup in the glossy screen?”
It’s a safety thing. Way, _way_ too frequently I’ve picked up my laptop bag and it felt…warm. I unzipped it and heared a screaming fan. At some unguessable point in the recent past, the MacBook got jostled just enough to twitch the screen sensor and it woke up.
Inside a sealed bag whose thick padding acted as thermal insulation. Result: a white-hot $1500 computer. That can’t be good. If there are any weak points in the hardware, that sort of abuse will cook ’em right into a hardware failure.
Worse: when this sort of thing happens and I pull the machine out, I prepare myself for percolator-like noises signifying a head crash. If I had KNOWN that my MacBook was awake, I certainly wouldn’t have run for the train. And when I caught my train, I wouldn’t have simply dropped my bag on the seat in exhaustion. Even when it’s a padded case and a padded seat, you should _never_ drop a running MacBook. Because — see if you can follow this, Mr. Wake On Lid Open feature — IF THE HARD DRIVE IS SPINNING ALL OF ITS DATA WILL GET CREAMED by the jostling and bouncing.
Okay? I’ve only had one unrecoverable drive crash in my life, and it happened when I accidentally dropped my MacBook a whole three-quarters of an inch while it was waking from sleep.
Ideally, “Disable Wake On Lid Open” would be a system pref instead of something that can only be done via the command line. But if this were an ideal world, the normal bumps and jostles that a notebook experiences in transit wouldn’t be enough to wake the machine.
At least Prefs has a “sleep hard drive whenever possible” option. It’s intended to conserve the battery but it probably protects your data, too. The next time you slide your MacBook out of the way a little to make room for your beverage and wind up bumping it right into a wall, think about that option. Ideally, you’ll be thinking “Boy, I’m glad I turned it on; there’s an excellent chance that the drive heads were safely parked when that happened.”