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: 
That’s just paranoia. Hibernate mode is perfectly healthy for an SSD. A SSD will last about 2-4 years of continuous writes. This means the time for which the SSD is powered. I have a 4 year old computer and its HD has been powered for 1.5 years (according to disk utility). Your SSD can definitely last a longer time.
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.
> 
> 
>