28 September 2014

No sleep for you Mac mini

Our Mac mini (a late 2012 model running the latest OS X 10.9.5) has just decided that it doesn’t want to wake from sleep anymore. It would normally wake when accessed from my MacBook for Screen Sharing, or from our Apple TV for streaming with iTunes Home Sharing, which we use all the time (Peppa Pig!). My feelings: frustration with a tinge of déjà vu.

This was all working fine before Apple’s recent round of software updates: iOS 8, OS X 10.9.5 and Apple TV 7.0.0. I don’t know which of those updates is the culprit, if any.

I spent the morning looking for a solution. I tried playing with network settings, resetting all the devices, and even resetting the Parameter Memory (PRAM) in the Mac, all to no avail. And I definitely have the salient “Wake for network access” preference set in Energy Saver Preferences. I’ve submitted a bug report to Apple, but who knows what will come of that.

This isn’t the first time we have had this type of issue. If I remember correctly, the first version of OS X Mountain Lion (10.8) broke “wake from sleep” for us, and it wasn’t fixed until 10.8.2. I vaguely remember other issues when running Lion too. There is a smell of unreliability around this “wake from sleep” stuff.

After a wasted morning, I started wondering: why do I even care about this? I can just prevent the Mac mini ever going to sleep and be done with it. Sure, it’ll cost a bit more in electricity usage, but compared to all my other expenses, not a big deal.

I think part of the reason that I persist with this folly is that I just feel like it should work; it’s the correct solution! Apple has a cool technology with its Bonjour Sleep Proxy service, which has been around for a while, and should “just work”. And I’m using all modern Apple hardware, with the latest software, so there should be minimal compatibility issues; why doesn’t it work! And it feels wrong to waste electricity, when I don’t have to.

But that’s all wishy-washy thinking; I should be looking at the facts:

  • I measured the Mac mini’s power usage: 1 Watt when sleeping, 8 Watts when fully awake. It would be even less when the hard drives aren’t spinning (but, I didn’t measure that). At $0.35 per kWh (my highest tariff), it costs about $25 to run the Mac mini at full power for an entire year. That’s not much.
  • The time to wait for the Mac mini to wake from sleep can range from a few seconds (fine), to tens of seconds (not so fine). However, when the Mac is fully awake, access is instantaneous; bonus!
  • Sometimes we see flaky behavior with Home Sharing, and I usually fix it by restarting the Apple TV, or by restarting iTunes on the Mac mini. I don’t know if “wake from sleep” comes in to play here, but it might.
  • I can schedule the Mac to completely shutdown overnight for at least six hours, which will save energy (and $6 a year, pffft). Resetting iTunes every night probably doesn’t hurt either.

Considering the above facts, the course of action is clear: no sleep for you Mac mini!