How do I copy my internal SSD to an external SSD?

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Level 1

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How do I copy my internal SSD to an external SSD?

I want to make a backup of my internal 256 GB SSD. I bought a 480 GB SSD and connected it via USB. How do I copy my internal SSD to the external SSD? This would be a bootable external SSD.

I tried Disk Utiliy > Restore. It gave me this error message:

The source volume cannot be restored because it has a broken seal
Could not validate source - Invalid argument
The operation couldn’t be completed. (OSStatus error 22.)

Then I tried Migration Assistant. This will only copy between computers (Mac or Windows), not from an internal SSD to an external SSD.

I downloaded Carbonite but I couldn't see how to copy an SSD.

What should I try next?

Posted on Oct 21, 2021 5:39 PM

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Answer 1

Top-ranking reply

babowa

Level 9

78,568 points

Oct 21, 2021 6:26 PM in response to Thomas Kehoe

You don't say which Mac OS you are running. You can make a bootable clone with CarbonCopyCloner - a simple one step process up until OS Big Sur; Big Sur made it a bit more involved, but you can read about it here: (I've used CCC for years)

https://bombich.com/

When you first plug in your new external, don't forget to use Disk utility to first erase and format it for Mac. An external drive does not need anything to be functional.

FWIW, just saw you have a Kingston: I've never found a product from that company that was reliable. I'd try to return it and buy one from a recommended Mac-centric seller such as OWC

www.macsales.com

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Answer 2

Oct 22, 2021 8:52 AM in response to Thomas Kehoe

Hi Thomas,

The easiest way to "clone" your data over to the external SSD would be to do the following:

In Disk Utility, erase (format) your external SSD as APFS, using the GUID Partition Table/Map as the scheme.
Download macOS Big Sur (or in a couple of days, macOS Monterey) from the App Store.
When the installer is downloaded, it should open itself.
You should be asked to select a destination. Choose the external SSD and start the install.
When the installation is finished, you can import your data from the internal SSD when prompted to transfer from another Mac. (This won't remove any data on the internal SSD.)
To swap between the internal SSD and the external SSD, select the startup disk you want to use in System Preferences -> Startup Disk.

If you want to make a true exact clone, that is technically possible, but it requires use of the command line and several steps in preparation. This kind of clone would use the underlying technology that Disk Utility's "Restore" button uses.

EDIT: As mentioned by Grant, you'll need to permit booting from external media if your Mac has the T2 Security Chip (but not M1 or future Apple silicon). To do so, please see this article: About Startup Security Utility - Apple Support

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Answer 3

Oct 21, 2021 6:19 PM in response to Thomas Kehoe

try installing macOS on the external drive. If that works, you can boot from it, and use setup assistant to copy your files.

Using the drive-maker's disk Utilities is NOT recommended. You should always ERASE a new drive with Disk Utility.

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Answer 4

Thomas Kehoe Author

Level 1

92 points

Oct 21, 2021 6:31 PM in response to babowa

I'm running Big Sur. I'll try CarbonCopyCloner.

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Answer 5

Thomas Kehoe Author

Level 1

92 points

Oct 22, 2021 9:36 AM in response to Encryptor5000

I may have found the problem in your plan. Your step #1 formats the SSD as APFS but Apple says to format as Mac OS Extended to make a bootable drive. Are you sure that a MacBook can boot from a APFS drive?

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Answer 6

Oct 22, 2021 6:33 PM in response to Thomas Kehoe

Thomas Kehoe wrote:

I downloaded and installed Big Sur on the external SSD. The problem with your plan is that Migration Assistant transfers data from one computer (Mac or Windows) to another computer. It doesn't recognize an external SSD as a computer.

It's possible that your plan might work if the external SSD were bootable. My MacBook won't boot from the external SSD. I don't understand why. I'll work on figuring this out before I try Carbon Copy Cloner.

Can you please clarify the situation a bit more?

If the SSD was formatted correctly (Format: APFS, Scheme: GUID Partition Table/Map), and macOS is indeed installed onto the SSD, that will automatically make the SSD bootable.

What steps did you take to install macOS Big Sur onto the SSD?

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Answer 7

Thomas Kehoe Author

Level 1

92 points

Oct 22, 2021 9:51 AM in response to Thomas Kehoe

APFS disks may not be used as bootable install media.

That's the error message I got when I tried to run

sudo /Applications/Install\ macOS\ Big\ Sur.app/Contents/Resources/createinstallmedia --volume /Volumes/MyVolume

I'll erase and reformat the external SSD as Mac OS Extended and see if I can make a bootable drive.

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Answer 8

Oct 22, 2021 1:23 PM in response to Thomas Kehoe

A bootable Installer is like an Installer DVD.

It is a little drive (like a USB thumb drive) that contains a bootable MINIMAL system and a MacOS image and the Utilities needed to get that image installed, including Disk Utility.

It is NOT for creating a bootable drive DIRECTLY -- only indirectly, by booting from it as if it were an Installer DVD.

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Answer 9

Oct 22, 2021 10:35 PM in response to Thomas Kehoe

Interesting... your particular Mac doesn't have the T2 Security Chip, so it doesn't have the capability to block external boot.

I don't know of a way to resolve this issue, but you could try resetting NVRAM and resetting the System Management Controller (SMC).

Also, make sure that you don't have a firmware password set.

Does it work to boot the external SSD via another Mac? This helps determine if the fault lies with the SSD or with your particular Mac.

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Answer 10

Thomas Kehoe Author

Level 1

92 points

Oct 21, 2021 6:27 PM in response to Grant Bennet-Alder

I installed Big Sur on the external SSD. When I try to set the external SSD as the Startup Disk I get this error message:

An error occurred while setting “Kingston 480GB SSD” as the startup disk: 
The operation couldn’t be completed. 
(SDErrorDomain error 104.)

Do I need to run the following from the CLI?

sudo /Applications/Install\ macOS\ Big\ Sur.app/Contents/Resources/createinstallmedia --volume /Volumes/MyVolume

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Answer 11

Thomas Kehoe Author

Level 1

92 points

Oct 22, 2021 8:36 AM in response to Grant Bennet-Alder

Bootable. I want to be able to run the MacBook from the external SSD just like the internal SSD. If this works I'll wipe the internal SSD are reinstall the OS, apps, and my user folder. Hidden files are eating up disk space. I keep running out of disk space, then I try to figure what hidden files are taking up gigabytes of space. I cleared 40 GB of useless files a couple months ago but this space has been eaten up already. CleanMyMac is useless. Someone should develop an app that identifies useless files that you can delete. For example, I discovered that my MacBook had a copy of every attachment every texted to my iPhone. Now MS Outlook is taking up 25 GB. I don't have 25 GB of email but I can't figure out what files can be deleted.

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Answer 12

Thomas Kehoe Author

Level 1

92 points

Oct 22, 2021 10:46 AM in response to Encryptor5000

I reformatted the external SSD as Mac OS Extended. The command executed without a problem:

sudo /Applications/Install\ macOS\ Big\ Sur.app/Contents/Resources/createinstallmedia --volume /Volumes/MyVolume

Apple says that next step is to restart while holding down the Option key and select the external SSD as the startup disk. This opened Install OS X El Capitan. There wasn't an option for installing Big Sur. When I tried to install El Capitan I got an error message saying that a newer operating system had already been installed.

I have an Install macOS Big Sur in my Applications folder. There must be an Install macOS El Capitan hiding somewhere on my computer. I searched but couldn't find it.

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Answer 13

Thomas Kehoe Author

Level 1

92 points

Oct 22, 2021 12:06 PM in response to Thomas Kehoe

Unbelievable. I can't install Big Sur because I formatted the SSD as Mac OS Extended. Big Sur can only be installed on APFS drives.

This means that bootable drives can't be APFS and Big Sur can only be APFS. What is the latest operating system that can be used on a bootable drive?

Apple's How to create a bootable install drive says that Big Sur can be installed. Does anyone have instructions that work for creating a bootable external SSD?

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Answer 14

Thomas Kehoe Author

Level 1

92 points

Oct 22, 2021 12:09 PM in response to Thomas Kehoe

Maybe the problem is that I shouldn't use Apple instructions for How to create a bootable installer for macOS. What is a "bootable installer"? Is that an external drive (USB or SSD) that a MacBook can boot from? Or is it something else? Is it a computer that can install macOS on other computers? That's not what I'm trying to do.

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Answer 15

Thomas Kehoe Author

Level 1

92 points

Oct 22, 2021 7:47 PM in response to Encryptor5000

Encryptor5000 wrote:

If the SSD was formatted correctly (Format: APFS, Scheme: GUID Partition Table/Map), and macOS is indeed installed onto the SSD, that will automatically make the SSD bootable.

Yep, did all that. I installed Big Sur on the external SSD using Install macOS Big Sur (it'a an app). I ran it from my internal SSD. When that didn't boot I copied the app to the external SSD and ran the app. That didn't boot either. The error messages were That says "SDErrorDomain error 104".

The other things that won't boot:

DiskWarrior USB drive with El Capitan. My 2009 Mac Pro can run from this. I get the apple startup screen but it just stops there.
The HDD from my Mac Pro with El Capitan. I can select this as a Startup Disk but then it starts from the internal SSD.
I used Carbon Copy Cloner to copy the internal SSD to the external SSD. That says "SDErrorDomain error 104".

I googled the error message but I can't find any explanation of what it means.

Is there a security setting somewhere that says "Never start from an external drive"?

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How do I copy my internal SSD to an external SSD?

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