Ok, so according to https://www.apple.com/osx/what-is/security/ I should be able to encrypt ANY external drive..."with ease" using FileVault 2.

I have a brand new (empty) 2TB Fantom Drive model: GFP2000EU3 (Hitachi Drive)

Disk Utility:

  1. I tried to erase and format the drive to Mac OS Extended (Journaled, Encrypted) Returned Error: "A GUID Partition Table (GPT) partitioning scheme is required."
  2. Selected Logical Volume in left list, then went to Partition tab, clicked on dropdown, showing "Current," changed it to 1 partition, clicked Options button, then selected GUID Partition Table radio button > clicked OK, then Apply on main window. No errors came during this step.
  3. Tried step 1 again, different error message: "Unable to create a new Core Storage logical volume group."


  1. Attempted ctrl+click>Encrypt *Drive Name* drive icon on my desktop, same error: "Unable to create a new Core Storage logical volume group."

I also tried a disk repair before trying again. Then tried all these steps again in Recovery Mode (command+R during startup), then tried under Safe Mode (holding shift at startup), and then under another user account. All come back with same error: "Unable to create a new Core Storage logical volume group."

Update 1:: I was able to successfully encrypt a 8gb Sandisk thumb drive. Still need to take care of the 2TB.

$diskutil list

#:                       TYPE NAME                    SIZE       IDENTIFIER
0:      GUID_partition_scheme                        *2.0 TB     disk3
1:                        EFI EFI                     209.7 MB   disk3s1
2:                  Apple_HFS MyDrive                 2.0 TB     disk3s2

After chats with Apple tier 1 & Senior Support, they've ran CaptureData and a Systems Engineer is looking into this, may take a day or two. They said they have little to no documentation yet on my problem. Seems unlikely that I'm the only one...

Update 2: I received repair authorization from Fantom and overnighted the drive (at my expense). After inspection I received this message: "We've completed diagnostics on your drive and regret to inform you that the hard disk inside the case has failed. As such, the damage is now beyond our ability to repair- we will replace the disk drive mechanism and return the repaired unit."

I find this interesting, because I may not have found out about this problem until after I loaded critical data on the drive. I was able to format the drive and copy to and from the drive without issue...encrypting the drive exposed the problem. I still need to confirm that the "repaired unit" will encrypt as expected, hopefully I will receive that back soon.

Final update: after receiving the new drive, everything encrypted as expected. My advice is to try to encrypt every drive when you first get it, as a failure may detect some glitches that you'd want to see sooner rather than later...


3 Answers 3


I understand that you're running into issues, so this is going to be more for others looking for info on this topic. Encrypting non-boot volumes should be a relatively easy process in OS X 10.8.x and later.

To encrypt a non-boot volume:

  1. Right-click on the volume you want to encrypt

  2. Select the Encrypt… command

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  1. When prompted, enter a password and (optionally) a password hint.

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The drive will momentarily disappear from the desktop (to initialize the encryption) then re-appear.

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  • Note under normal operation, when you plug in the drive next time, you should be prompted for the password you setup during steps above. If the drive doesn't appear on desktop, you may be able to see it under Disk Utility. Disk Utility will give you the option to enter password to decrypt and mount it from there.
    – webaholik
    Apr 16, 2015 at 14:23
  • 2
    This option is no longer available in macOS Mojave from the contextual menu. Not that I can see, anyway!
    – jlbang
    Oct 12, 2018 at 3:37
  • 1
    @jlbang: see this answer for an explanation. Sep 22, 2019 at 17:23

I wanted to mention that this process will not work on your Flash drive as it comes formatted as a FAT Partition. You will need to reformat the drive to Mac OS Extended (Journaled) then when you enable the Encryption it will be be converted to Mac OS Extended (Journaled, Encrypted)

You will be able to reformat your flash drive using Disk Utility found in your /Applications/Utilities folder.


In High Sierra I don't see the "Encrypt" option in the contextual menu. I didn't find a general solution for this. But I did find a solution for my specific use case: encrypt an external harddisk with Time Machine backups. Simply go to the Time Machine settings, "Add or Remove Backup Disk..."

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and check the "Encrypt backups" checkbox:

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