Format Filevault Encrypted HD

[wngraham]

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]

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]

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?

 

[Weaselboy]

...and if you don't know said password?

If you are booted from a USB key you can just select the drive name at the top (like Seagate 500GB) and erase the entire disk from there. No PW is needed.

 

[ikev85]

You can also open terminal type

sudo diskutil cs list

find the UUID at the top and type

sudo diskutil cs delete <UUID>

 

[Bear]

...

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.