I'm running Filevault on my internal hard drive, but I realized that I never encrypted my external drive. Currently it's running Mac OS Extended (Journaled) and I'm not seeing any encrypt options anywhere (right click in Finder, disk utility, etc...). How can I encrypt this drive in place without having to erase all the data first? I could restore the data from a Time Machine backup but that sounds very tedious and time consuming. If there is a faster way I'd like to attempt that first.

1 Answer 1


Normally the option to encrypt the drive can be found by right clicking the drive's icon in finder and selecting 'Encrypt "DISKNAME"'. You will not see the encryption option if the disk is using Master Boot Record or Apple Partition Map as the partition scheme.

This is because High Sierra encryption actually converts the Mac OS Extended (Journaled) to Apple File System (APFS), and this cannot be done on a Master Boot Record or Apple Partition Map partitioned drive.

You can check the disk partition type in Disk Utility.

Right click encryption option

  • 1
    Ah ok I was under the impression that APFS was only available for SSD’s (this external is a mechanical drive). I guess in that case a reformat is in order then. Nov 29, 2017 at 19:13
  • 2
    Stock SSDs in Apple devices are automatically converted to APFS when going to macOS 10.13, but HDDs must be converted manually. Hybrid drives, like Apple's Fusion Drive, currently are not supported by APFS. A disk can only be formatted to APFS when using the GUID Partition Map.
    – drivec
    Nov 29, 2017 at 19:43

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