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

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customizer Author

Level 1

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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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Answer 1

Top-ranking reply

Lexiepex

Level 6

14,102 points

Jul 15, 2017 5:37 AM in response to customizer

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.

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Answer 2

Lexiepex

Level 6

14,102 points

Jul 15, 2017 10:49 AM in response to customizer

open DiskUtility when the external is connected. In this picture I have connected a disk with 3 partitions. You select the external then select the Partition button. Then a window pops up where you select the partition type, select GUID partition table, and under that the format, select Mac OS Extended (journaled), and do that.

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Answer 3

customizer Author

Level 1

8 points

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?

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Answer 4

Lexiepex

Level 6

14,102 points

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.

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Answer 5

customizer Author

Level 1

8 points

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.

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Answer 6

babowa

Level 9

78,441 points

Jul 15, 2017 10:49 AM in response to customizer

FYI for future consideration: whenever I get a new external hard drive, I format it immediately before use and that includes formatting it with the GUID partition scheme (aside from erasing some of the superfluous software present on that drive). That way, it is done and I don't have to think about it again.

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Answer 7

customizer Author

Level 1

8 points

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?

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Answer 8

Csound1

Level 9

60,033 points

Jul 15, 2017 6:01 AM in response to customizer

The standard way of formatting is with a GUID partition table, yours is non-standard.

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Answer 9

Esquared

Level 6

12,409 points

Jul 15, 2017 6:02 AM in response to customizer

APFS needs reformatting anyway.

But the bigger question is: if you have no possibility to park your data elsewhere, that means that at least for some of your data you don't have a backup... Correct?

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