Question: I encrypted my Time Machine backup (A Western Digital 2tb external drive) then realised that Airport wont mount the backup over wifi, so am currently decrypting the drive (via Disk Utility).

I found the command:

```
diskutil cs list

```

which shows me the progress of the operation (it took a while to register at the under the the menu-bar icon).

Here's a snippet from the output:

```
    Sequence:               13
    Encryption Status:      Unlocked
    Encryption Type:        None
    Encryption Context:     Present
    Conversion Status:      Converting
    Has Encrypted Extents:  Yes
    Conversion Direction:   backward

```

Encrypting the backup took about 24 hours, and the time machine icon currently shows 'Decryptig Backup Disk (28%)'.

My question is: can I eject the drive without losing the backup? Will the decryption continue when I mount the drive again?

TIA, Tim

Answer: 
Although this is an old question, I would like to update it with my answer because it is still relevant to me.

<http://blog.alutam.com/2012/04/01/optimizing-macos-x-lion-for-ssd/#hibernation>

```
sudo pmset -a hibernatemode 0
sudo rm /var/vm/sleepimage

```

> 
> We do not recommend modifying hibernation settings. Any changes you make are not supported. If you choose to do so anyway, we recommend using one of these three settings. For your sake and mine, please don’t use anything other 0, 3, or 25.
>  hibernatemode = 0 (binary 0000) by default on supported desktops. The system will not back memory up to persistent storage. The system must wake from the contents of memory; the system will lose context on power loss. This is, historically, plain old sleep.
>  hibernatemode = 3 (binary 0011) by default on supported portables. The system will store a copy of memory to persistent storage (the disk), and will power memory during sleep. The system will wake from memory, unless a power loss forces it to restore from disk image.
>  hibernatemode = 25 (binary 0001 1001) is only settable via pmset. The system will store a copy of memory to persistent storage (the disk), and will remove power to memory. The system will restore from disk image. If you want “hibernation” – slower sleeps, slower wakes, and better battery life, you should use this setting.
> 
> 
>
I actually prefer [SmartSleep](http://www.jinx.de/SmartSleep.html). Using this little app gives you the best of both worlds. When you sleep your Mac (close the lid), SmartSleep will decide based on your remaining battery capacity whether to write the hibernation image or not. This is useful, because if you ever find yourself in a tricky situation, where your battery runs out, you will not loose your data.

I have been using SmartSleep ever since I had a SSD (2-3 years now) and really appreciate it. It also offers some nice shortcuts, like `caffeinate` or instant hibernation.