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How to encrypt an external drive without deleting the drive before?

I like to encrypt my external USB drive, which is formatted as "MacOS extended journaled".



When I choose the command "encrypt" and enter a password I get the result:


"A GUID Partition Table (GPT) partitioning scheme is required"



I have no possibility to park my data elsewhere to delete/repartition my drive.



How can I solve the problem please?



Because I'm curious: Is that a bug in macOS?



If so: Can one expect that the problem will not persist, when a new file system APFS will be introduced in macOS High Sierra at the end of the year?



Thanks.

MacBook Pro (Retina, 13-inch,Early 2015), macOS Sierra (10.12.5), null

Posted on Jul 15, 2017 5:08 AM

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Posted on Jul 15, 2017 5:37 AM

No it is not a bug, but you have to partition as GUID Partition Table as the message says. Copy everything on the drive to another drive or a folder on your mac (if you have enough space), then partition/erase, then copy everything back again.

12 replies

Jul 15, 2017 5:58 AM in response to Lexiepex

Thanks for your reply Lexiepex.


As I wrote I cannot park my data anywhere.


So I have to relinquish, I cannot encrypt.


I wonder, that the standard way of the macOS of formatting prohibits encryption completely.


Are you really sure that there is technically absolutely no way to offer a standard formatting which does not prohibit encryption?


And:
Is there anyone who knows an answer to my last question in the original post?

Jul 15, 2017 6:14 AM in response to customizer

Your last question: probably there is someone, but not here.

I have really no idea about it but I expect it not to change anything for your problem.

Can you not rent or borrow a disk to copy the data?

GUID Partition Table is not just a gimmick, the (alternative) MasterBootRecord has serious limitations (max 4 partitions, max size, and so on) and is not used much anymore. If you use a cloning app to have a bootable backup clone you also have to have GUID PT.

Lex

btw: I am not so sure that APFS requires reformatting, it is more the handling of the data, address tables, registers and such.

Jul 15, 2017 8:53 AM in response to Lexiepex

@all
Thanks for your helpful answers.


@esquared
I have a time machine backup from all my data.
But I do not feel comfortable to delete my data on the HD I speak about, because than I had to accept that during the process, there's only one copy (inside my time machine backup).


@lex

Is there a screenshot please, which explains how I have to delete, reformat and apply the GUID?
I will try to borrow a HD somewhere.

Jul 15, 2017 10:56 AM in response to Lexiepex

Thanks, Lexipex 🙂 Got it.


I didn't know that it's neccessary to create a partition when you like to keep the option to encrypt.
In the future I will alway practice it like you suggested, babowa.


For curiosity:

Is there any relevant disadvantage of such a GUID table, if you do not encrypt?
If not, the question (for me) is, why Apple does not offer to partition in that way as a default?

How to encrypt an external drive without deleting the drive before?

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