Cloning Big Sur with the dd command

[Carlos-TM]

I’ve been cloning my Hackintoshes since the El Capitan days using SuperDuper! and Apple’s Disk Utility’s Restore feature. Others have used Carbon Copy Cloner successfully as well. One time I resorted to macOS asr command to clone Catalina, with one or both of the two lines below, booting from a different macOS instance:

sudo asr restore --source /dev/disk7s1 --target /Volumes/Untitled --erase

sudo asr restore --source /Volumes/Catalina --target /Volumes/Untitled --erase

But come Big Sur, these resources no longer work, or, in the case of Carbon Copy Cloner, perhaps cloning can be made to work through a long and convoluted procedure.

Well, I have used dd to clone Big Sur. Initially in Linux, but then also in macOS. This is what I did:

Booted to Catalina using OpenCore.

Ran “diskutil list” to determine the /dev assignments. The source for the dd command, a container holding only the Big Sur installation, was “synthetized” disk #3, and the target was an empty container identified as “synthetized” disk #9. I ran:

sudo dd if=/dev/disk3 of=/dev/disk9 bs=4096 conv=sync,noerror

I kept checking progress with control-t.

There you have it. The result was a fully functional clone of my Big Sur 11.2.3.

 

[pastrychef]

I’ve been cloning my Hackintoshes since the El Capitan days using SuperDuper! and Apple’s Disk Utility’s Restore feature. Others have used Carbon Copy Cloner successfully as well. One time I resorted to macOS asr command to clone Catalina, with one or both of the two lines below, booting from a different macOS instance:

sudo asr restore --source /dev/disk7s1 --target /Volumes/Untitled --erase

sudo asr restore --source /Volumes/Catalina --target /Volumes/Untitled --erase

But come Big Sur, these resources no longer work, or, in the case of Carbon Copy Cloner, perhaps cloning can be made to work through a long and convoluted procedure.

Well, I have used dd to clone Big Sur. Initially in Linux, but then also in macOS. This is what I did:

Booted to Catalina using OpenCore.

Ran “diskutil list” to determine the /dev assignments. The source for the dd command, a container holding only the Big Sur installation, was “synthetized” disk #3, and the target was an empty container identified as “synthetized” disk #9. I ran:

sudo dd if=/dev/disk3 of=/dev/disk9 bs=4096 conv=sync,noerror

I kept checking progress with control-t.

There you have it. The result was a fully functional clone of my Big Sur 11.2.3.

How much data was cloned and how long did it take? The last time I used dd to do the same, it took forever and a day.

 

[Carlos-TM]

How much data was cloned and how long did it take? The last time I used dd to do the same, it took forever and a day.

My Big Sur installation is 70 GB, system files only, my data files are somewhere else. With physical drives connected to the motherboard, dd takes about 30 minutes. With drives connected via USB 3, over an hour. I was surprised; my past experiences with dd were painfully slow.

 

[Middleman]

That's a very handy, thanks for this! With the increasing restrictions by Big Sur on Superduper and Carbon Copy Cloner on not being able to dupe a complete copy, tools like these are essential for us.