Trying Big Sur from external boot drive question

Started 9 months ago | Discussions
James C. Murray Senior Member • Posts: 2,085
Trying Big Sur from external boot drive question

If I clone my internal drive, (Carbon Copy Cloner), to an external SSD, boot from it and update it to Big Sur am I likely to have any problems other than perhaps reduced speed?

I would like to try this to see where I may have problems with apps, Capture One 20 in particular. The idea of course is being able to return to my internal Catalina OS if things do not work out.

Capture One are advising to hold off on Big Sur until they can say there are no problems and I am not about to ignore their advice.

Thanks.

Edited to add that I am using a late 2015 iMac with Catalina at the moment.

 James C. Murray's gear list:James C. Murray's gear list
Canon EOS 7D Mark II
DavidHH Regular Member • Posts: 217
Re: Trying Big Sur from external boot drive question

Yes there are some caveats if you are using Cloning Software e.g. Carbon Copy Cloner. The caveat identified by Carbon Copy Cloner I would assume could impact all cloning software. I would proceed with a lot of caution if you need to depend on making a Clone Copy of Big Sur.

Bombich Software (makers of Carbon Copy Cloner) are experts in this field and they are raising "Yellow Flags".

See attached Blog post from Bombich Software.

https://bombich.com/blog/2020/11/03/yes-you-can-have-bootable-backups-on-macos-big-sur

-- hide signature --

DavidHH

 DavidHH's gear list:DavidHH's gear list
Canon G1 X III
Frits Senior Member • Posts: 1,268
Re: Trying Big Sur from external boot drive question

You will be fine to do this (clone Catalina to an external SSD and then update to Big Sur while booted on the SSDand keep Catalina on the internal drive).

I run my iMac from an external SSD since some time. I cloned the internal fusion drive onto the SSD when OSX was High Sierra and updated the SSD to Catalina when it came out.

I keep High Sierra on the fusion drive and (very) occasionally use it when I want to do something in Photoshop 6.

I have updated the SSD from Catalina to Big Sur without any issues and all works fine - including Capture One 20.

I hope this helps.

-- hide signature --

Frits

Ribies New Member • Posts: 15
Re: Trying Big Sur from external boot drive question

I use and NVME M2 external boot drive on my 2017 27" iMac and the drive updated to Big Sur with no problems. One comment on updating to Big Sur, there have been quite a few comments on "black screens". I did get "black screens but simply walked away, only to come back and find a loading screen and everything was fine. I think some people may be getting impatient or panicking when this happens and then they interrupt the update process. It would be helpful if Apple provided a description of the update process.

Frits Senior Member • Posts: 1,268
Re: Trying Big Sur from external boot drive question

I think you’re spot on wrt black screen. Apple clearly states that updating to Big Sur causes several restarts. I saw tat also while updating, just left it do its thing which it did without any real issues.

-- hide signature --

Frits

OP James C. Murray Senior Member • Posts: 2,085
Re: Trying Big Sur from external boot drive question

DavidHH wrote:

Yes there are some caveats if you are using Cloning Software e.g. Carbon Copy Cloner. The caveat identified by Carbon Copy Cloner I would assume could impact all cloning software. I would proceed with a lot of caution if you need to depend on making a Clone Copy of Big Sur.

I would  clone to an external,  (Samsung T5),  and then boot from there and then update etc. so I hope I would not be putting my internal iMac boot drive in jeopardy. I also have another CCC and TM backup of the iMac.

Bombich Software (makers of Carbon Copy Cloner) are experts in this field and they are raising "Yellow Flags".

See attached Blog post from Bombich Software.

https://bombich.com/blog/2020/11/03/yes-you-can-have-bootable-backups-on-macos-big-sur

That is worth a read. I think Bombich sent it to registered owners. I believe there are some procedures required with CCC with computers having the T2 chip but that does not apply to my  vintage iMac.

Thanks for your response.

 James C. Murray's gear list:James C. Murray's gear list
Canon EOS 7D Mark II
OP James C. Murray Senior Member • Posts: 2,085
Re: Trying Big Sur from external boot drive question

Thanks Frits and Ribies for your help, I'll give it a try although I expect that it may be a bit slow  given the USB ports on the iMac, I guess they are the bottleneck.

 James C. Murray's gear list:James C. Murray's gear list
Canon EOS 7D Mark II
Frits Senior Member • Posts: 1,268
Re: Trying Big Sur from external boot drive question

I have my SSD connected to a USB 3 port - definitely faster than the internal fusion drive. Very happy running my iMac like this since some time already.

-- hide signature --

Frits

OP James C. Murray Senior Member • Posts: 2,085
Re: Trying Big Sur from external boot drive question

Frits wrote:

I have my SSD connected to a USB 3 port - definitely faster than the internal fusion drive. Very happy running my iMac like this since some time already.

My iMac has an internal SSD rather than the Fusion,  which as Tom_N tells me, is about 3 times the speed of the data transfer through the USB ports on a Late 2015 iMac regardless of the speed of the external so that is the chokepoint.

The iMac does have Thunderbolt 2 ports but finding connections for them seems to be a problem.

I am looking at replacing the iMac but want to see a bit more of where and when Apple are going with their Silicon and who will still be supporting Apps.

Thanks.

 James C. Murray's gear list:James C. Murray's gear list
Canon EOS 7D Mark II
Rich42 Senior Member • Posts: 2,104
Re: Trying Big Sur from external boot drive question

James C. Murray wrote:

If I clone my internal drive, (Carbon Copy Cloner), to an external SSD, boot from it and update it to Big Sur am I likely to have any problems other than perhaps reduced speed?

I would like to try this to see where I may have problems with apps, Capture One 20 in particular. The idea of course is being able to return to my internal Catalina OS if things do not work out.

Capture One are advising to hold off on Big Sur until they can say there are no problems and I am not about to ignore their advice.

Thanks.

Edited to add that I am using a late 2015 iMac with Catalina at the moment.

I suggest mounting the blank drive either via USB C or USB A port, downloading Big Sur and directing the install to the external drive.

The install will complete and boot into the Big Surface drive. Then it will prompt you to run migration assistant to bring all your programs and settings to the Big Sur drive.

That's what I've done. With no problems.

I use Super Duper all the time for (bootable) backups and installs. I see no advantage to cloning your Catalina install to an external drive, booting, into that and upgrading that volume with Big Sur.

Rich

JPAlbert Senior Member • Posts: 1,041
Re: Trying Big Sur from external boot drive question

"If I clone my internal drive, (Carbon Copy Cloner), to an external SSD, boot from it and update it to Big Sur am I likely to have any problems other than perhaps reduced speed?"

Actually, that would be a very prudent method by which to try out Big Sur BEFORE you "commit to it" on your internal drive.

I just installed Big Sur onto an old platter-based drive I had this afternoon.
The install went ok, I really haven't fooled with it since then.

My drive is an older HDD and not fast. "Test purposes" only.
If you do your "test install" to an SSD, things will probably go much faster.

OP James C. Murray Senior Member • Posts: 2,085
Re: Trying Big Sur from external boot drive question

Rich42 wrote:

James C. Murray wrote:

If I clone my internal drive, (Carbon Copy Cloner), to an external SSD, boot from it and update it to Big Sur am I likely to have any problems other than perhaps reduced speed?

I would like to try this to see where I may have problems with apps, Capture One 20 in particular. The idea of course is being able to return to my internal Catalina OS if things do not work out.

Capture One are advising to hold off on Big Sur until they can say there are no problems and I am not about to ignore their advice.

Thanks.

Edited to add that I am using a late 2015 iMac with Catalina at the moment.

I suggest mounting the blank drive either via USB C or USB A port, downloading Big Sur and directing the install to the external drive.

The install will complete and boot into the Big Surface drive. Then it will prompt you to run migration assistant to bring all your programs and settings to the Big Sur drive.

That's what I've done. With no problems.

I use Super Duper all the time for (bootable) backups and installs. I see no advantage to cloning your Catalina install to an external drive, booting, into that and upgrading that volume with Big Sur.

Rich

Thank you for the reply, your suggestion is something I had not thought of but it looks clean and makes a lot of sense. I went looking into Migration assistant to learn a bit more and came across the procedures recommended for a clean install. While that is probably a bit more than I need for what I want to do at the moment it does point me in a good direction when I replace the current machine.

Thanks again.

 James C. Murray's gear list:James C. Murray's gear list
Canon EOS 7D Mark II
OP James C. Murray Senior Member • Posts: 2,085
Re: Trying Big Sur from external boot drive question

JPAlbert wrote:

"If I clone my internal drive, (Carbon Copy Cloner), to an external SSD, boot from it and update it to Big Sur am I likely to have any problems other than perhaps reduced speed?"

Actually, that would be a very prudent method by which to try out Big Sur BEFORE you "commit to it" on your internal drive.

I just installed Big Sur onto an old platter-based drive I had this afternoon.
The install went ok, I really haven't fooled with it since then.

My drive is an older HDD and not fast. "Test purposes" only.
If you do your "test install" to an SSD, things will probably go much faster.

Thanks JP, and all who replied, when you are not too sure if you really know what you are doing it is re-assuring to get advice on where you are going.

Thanks.

 James C. Murray's gear list:James C. Murray's gear list
Canon EOS 7D Mark II
Tom_N Forum Pro • Posts: 19,087
Re: Trying Big Sur from external boot drive question

James C. Murray wrote:

If I clone my internal drive, (Carbon Copy Cloner), to an external SSD, boot from it and update it to Big Sur am I likely to have any problems other than perhaps reduced speed?

There is a possibility that the Startup Disk Preferences panels in Mojave and Catalina won't offer the choice of booting from an external Big Sur startup disk. This is because Big Sur uses security features that older versions of the OS do not understand.

The workaround is to hold down the Option key when restarting the Mac so that you can select the Big Sur volume from the firmware's Startup Manager.

OP James C. Murray Senior Member • Posts: 2,085
Re: Trying Big Sur from external boot drive question

Tom_N wrote:

James C. Murray wrote:

If I clone my internal drive, (Carbon Copy Cloner), to an external SSD, boot from it and update it to Big Sur am I likely to have any problems other than perhaps reduced speed?

There is a possibility that the Startup Disk Preferences panels in Mojave and Catalina won't offer the choice of booting from an external Big Sur startup disk. This is because Big Sur uses security features that older versions of the OS do not understand.

The workaround is to hold down the Option key when restarting the Mac so that you can select the Big Sur volume from the firmware's Startup Manager.

Thank you Tom, that would have been a surprise that would have cost me a lot of search time.

 James C. Murray's gear list:James C. Murray's gear list
Canon EOS 7D Mark II
Keyboard shortcuts:
FForum MMy threads