Switch APFS Encrypted to APFS (non-encrypted)

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Switch APFS Encrypted to APFS (non-encrypted)

I hadn't realized it before now, but my iMac Pro shipped with the internal SSD formatted as APFS Encrypted (according to Disk Utility). I have no idea why that was the default choice, and I don't really need or want the overhead of encryption, as my primary concern with the system is that it be as fast as possible, so it seems to me that I'd be better off if it was formatted as APFS only (without encryption). But I already have a ton of stuff installed. So, is it too late to change this? Would changing it from APFS Encrypted to APFS gain me any performance? And would it require reformatting the drive and reinstalling the OS and everything else?

I'm not talking about FileVault, BTW. Never used it, and never intend to.

iMac Pro (2017), macOS High Sierra (10.13.5), 4TB SSD, 128GB RAM

Posted on Jul 9, 2018 12:59 PM

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Answer 1

Barney-15E

Level 10

123,308 points

Jul 9, 2018 3:51 PM in response to Mysticfm

It would not have shipped that way as you would have no way to know the password to decrypt the disk.

You would need to know the password to decrypt the drive. Does it ask to decrypt on boot?

I don't know of a way to disable the encryption in the GUI unless it is FileVault, which you can turn off in the Security & Privacy System Prefs. In Terminal, you can use diskutil to decrypt the drive. Type man diskutil and look at the section for APFS.

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Answer 2

etresoft

Level 9

57,548 points

Jul 9, 2018 6:38 PM in response to Barney-15E

Barney-15E wrote:

It would not have shipped that way as you would have no way to know the password to decrypt the disk.

Apparently the iMac Pro is "special" About encryption on your iMac Pro - Apple Support

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Answer 3

etresoft

Level 9

57,548 points

Jul 9, 2018 6:39 PM in response to Mysticfm

Don't change anything. You can go ahead and enable FileVault to improve your security. But Apple designed that machine to be encrypted. I strongly suggest that you don't attempt to change it. As I mentioned to Barney-15E, the iMac Pro has a number of new security features and hardware. There is no way to tell what will happen if you try to circumvent any of that default behaviour.

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Answer 4

Mysticfm Author

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19 points

Jul 9, 2018 9:04 PM in response to Barney-15E

Articles I’ve read online suggested that there was a measurable drop in SSD performance (or drives in general) when encryption is enabled in APFS. In fact they even said the drop was present with the hardware encryption, albeit less so.

I guess it doesn’t matter much, if that’s essentially baked into the iMac Pro. Based on this thread’s responses, I’m not going to worry about it.

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Answer 5

Barney-15E

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123,308 points

Jul 9, 2018 5:22 PM in response to etresoft

etresoft wrote:

Barney-15E wrote:

It would not have shipped that way as you would have no way to know the password to decrypt the disk.

Apparently the iMac Pro is "special" About encryption on your iMac Pro - Apple Support

I guess that solves the passcode problem.

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Answer 6

Mysticfm Author

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19 points

Jul 9, 2018 6:42 PM in response to etresoft

Thanks for the info and the link. I didn’t know that the iMac Pro was “special” in this regard, either. I saw numerous people talking online about enabling encryption with APFS, but no one talking about disabling it. I guess that’s why ... maybe it’s just the iMac Pro that ships with it enabled, and that’s the way it is supposed to stay. Well, I guess that’s okay with me, then … I just didn’t want to be surrendering any SSD performance needlessly if there was an alternative.

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Answer 7

Barney-15E

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Jul 9, 2018 7:11 PM in response to Mysticfm

What makes you think you would be "surrendering any SSD performance" even if it didn't use hardware encryption?

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Answer 8

etresoft

Level 9

57,548 points

Jul 9, 2018 7:26 PM in response to Mysticfm

Mysticfm wrote:

I just didn’t want to be surrendering any SSD performance needlessly if there was an alternative.

The SSD in the iMac Pro is one of the fastest ever made.

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Answer 9

Barney-15E

Level 10

123,308 points

Jul 10, 2018 4:31 PM in response to Mysticfm

I never noticed any degradation, even on a spinning hard drive. Perhaps if your workflow revolves around running benchmarks, you see a performance hit.

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Switch APFS Encrypted to APFS (non-encrypted)

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