Format Filevault Encrypted HD

wngraham

macrumors regular
Original poster
Jun 8, 2006
149
0
Nashville, TN
I've decided to do a fresh install of Mountain Lion on my MacBook Pro (using a USB flash drive with the install disk on it).

My only concern is my harddrive has been encrypted using Filevault 2. Will this pose any issues? My plan was to boot into the USB drive then format the internal HD using Disk Utility, just as I always have when previously doing fresh installs.

Do I need to decrypt the disk first?

Any help or advice will be greatly appreciated.
 

EmpyreanUK

macrumors regular
Mar 6, 2011
216
12
You can indeed format an encrypted drive using the disk utility included in the OS X installer.

Before you're able to re-partition/format the drive, you have to unlock it first. When in Disk Utility, click on the drive you're planning to format, and then choose the toolbar option that says something along the lines of 'Unlock' or 'Verify'. You'll be issued with a password prompt: enter the password, and the drive will then mounted normally so that you're able to re-partition it, ready for the OS X installation.
 

richardsim7

macrumors regular
Oct 17, 2007
128
6
You can indeed format an encrypted drive using the disk utility included in the OS X installer.

Before you're able to re-partition/format the drive, you have to unlock it first. When in Disk Utility, click on the drive you're planning to format, and then choose the toolbar option that says something along the lines of 'Unlock' or 'Verify'. You'll be issued with a password prompt: enter the password, and the drive will then mounted normally so that you're able to re-partition it, ready for the OS X installation.
...and if you don't know said password?
 

ikev85

macrumors member
Mar 6, 2012
47
0
You can also open terminal type

sudo diskutil cs list

find the UUID at the top and type

sudo diskutil cs delete <UUID>
 

Bear

macrumors G3
Jul 23, 2002
8,089
4
Sol III - Terra
...

Do I need to decrypt the disk first?

Any help or advice will be greatly appreciated.
You don't need to decrypt the disk. You do want to erase the whole disk and not just the partition. After that the installation should work as normal. You will then need to enable FileVault 2 after the installation is finished.