Take the 2-minute tour ×
Super User is a question and answer site for computer enthusiasts and power users. It's 100% free, no registration required.

My current computer is getting old and I'm going to switch to a Mac when I replace it. I'm looking for a setup that has these properties:

  1. Turns on as quickly as possible
  2. I still have a usable battery even after years of using the computer primarily plugged in
  3. The drive is encrypted to the point that anyone who steals the machine while it's off won't be able to get any data off it. I'm thinking of common thieves who might true to use what they've stolen for identity theft, not people who can freeze my RAM immediately after I turn my computer off

I currently achieve this under Windows with the following configuration:

  1. When I use the computer while plugged in (often for weeks at a time), I take out the good battery and put it in the fridge, replacing it with an old battery that no longer holds a charge from the save computer
  2. I put the computer into hibernate when I'm not using it
  3. I encrypt every partition that contains anything important with TrueCrypt. In particular, the hibernation snapshot is encrypted so that you can't start it up unless you know the TrueCrypt password

Can I achieve this with a MacBook Pro? The reason that I'm concerned I may not be able to are:

  1. As far as I can tell, MacOS sleep is the closest analogue to hibernate that's available short of doing some hacking. After lots of looking I haven't been able to convince myself the FileVault 2 protects a computer while it's sleeping
  2. Sleeping Macs continue to require a small amount of energy. This means that the computer will be constantly drawing power and therefore aging the (non-removable) battery
share|improve this question

closed as primarily opinion-based by Tog, tapped-out, Simon Sheehan, mpy, Dave M Oct 23 '13 at 18:19

Many good questions generate some degree of opinion based on expert experience, but answers to this question will tend to be almost entirely based on opinions, rather than facts, references, or specific expertise.If this question can be reworded to fit the rules in the help center, please edit the question.

    
About hibernation, this might be relevant: badrit.com/blog/2013/1/30/hibernate-in-mac-os-x-lion. Quoting the relevant command: sudo pmset hibernatemode 3 –  Doktoro Reichard Oct 6 '13 at 23:37
add comment

3 Answers 3

You can easily enable hibernation on recent Macs (including my late-2008 MacBook Pro).

Macs have something called SafeSleep™, which means the system saves the RAM contents to disk and then enters sleep mode. When the battery reaches a critical level (I'm not clear on whether this is monitored, or if the system just loses power due to a flat battery), the system powers off. When power is restored, the system recognises the RAM image saved to disk, restores it, and it's as though you've resumed from hibernation; if the system never lost power, it just resumes from sleep mode.

SafeSleep is the default behaviour on portable Macs, while 'ordinary' sleep is the default on desktop Macs. The pmset command line utility can be used to change the default behaviour if desired. Use pmset -a hibernatemode # where # is: 0 for ordinary sleep, 3 for SafeSleep, and 25 for hibernate. See the pmset manual page (or type man pmset from a terminal) for more details.

As for encryption, I've no idea if TrueCrypt will do full disk encryption on a Mac, but I know that it has at least some Mac support; FileVault will perform full disk encryption on OS X Lion (10.7) and later, and you can encrypt Time Machine backups on those systems as well.

share|improve this answer
    
beat me to the punch! –  Hefewe1zen Oct 17 '13 at 1:39
add comment

The more recent macbooks aren't designed with "user removable" batteries so you can't really just swap it out on a whim. It was relatively easy to replace the battery on the pre-Retina macbooks, but now Apple has began gluing them down and other annoying things (check iFixIt).

Filevault 2 is the full disk encryption feature. Any hibernate file created by safe sleep will therefore be encrypted. You can't access a FV2 drive unless you have the master password.

There are several power management options in Mountain Lion. Safe Sleep is OSX's way of creating a hibernate file AND sleeping the system, if it runs out of battery life then you can still resume your system. These options can be set by pmset command in Terminal (a cursory google search will reveal a plethora of information regarding its usage)

share|improve this answer
add comment

I posted this question to the macrumors.com forum. Here's what I learned:

  • The community there regards worrying about battery health as essentially pointless with newer batteries, beyond running the battery down at least once a month
  • "The FileVault password can no longer be accessed while the machine is asleep. What those older articles(e.g., this one) are referring to is direct memory access (DMA) access to ram to grab a password. This is blocked starting with OS X 10.7.2 so is no longer an issue with newer Macs."

UPDATE: the paranoid can run "sudo pmset destroyfvkeyonstandby 1" as described on this blog, which in turn links to this Apple whitepaper on OS X 10.7.4.

share|improve this answer
1  
Hi. Author of that blog post here. 10.7.2 prevents the key from being accessed over DMA - yes. But, if the FV key isn't destroyed on sleep, then an attacker can resume the laptop and have unencrypted access to the hard disk over DMA exploits without needing your password. By destroying the FileVault key, you're negating this, because the disk is encrypted until after you unlock it on resume. Is a typically smash and grab thief this sophisticated? No. Does it hurt to be paranoid here? Probably not. –  MDMarra Dec 15 '13 at 2:53
add comment

Not the answer you're looking for? Browse other questions tagged or ask your own question.