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I am anticipating making the move from Catalina to Big Sur very soon, as 1) V11.2 of Big Sur will be released very shortly, 2) I've been testing V11.1 of Big Sur on an external SSD, and except for SuperDuper! and Tech Tool Pro, and a couple of very minor glitches, it works fine, and 3) it appears that Micromat is getting real close to releasing an Intel-based version of Tech Tool Pro that is compatible with Big Sur (just like Carbon Copy Cloner). I will then be left with an upgrade for SuperDuper!.

I just had an EMail conversation with Dave Nanian of Shirt Pocket Software about the status of SuperDuper! and Big Sur, and I did not get anything definitive from him. So, I would appreciate it if anyone can tell me if they are using the latest version of Carbon Copy Cloner, V5.1.23, with Big Sur and Intel-based Macs. Also, my use of CCC will be the same as it has always been for SuperDuper!: a complete erasure and formatting of the destination APFS-formatted volume, then a copy/clone of my system (everything on it) to that volume. That suits my needs just fine, as 1) I have never had the need for incremental backups, and 2) I do such backups once a week for both of my Mcs.

In any event, would appreciate feedback.

I'm using CCC with Big Sur and, if you follow your customary procedure of reformatting the APFS volume and cloning everything, all will be well. One caveat: Let CCC erase the destination volume as part of the cloning procedure rather than use Disk Utility to reformat and then use CCC. That worked better for me than reformatting with Disk Utility and then cloning with CCC.

Thanks for the report, and advice! With SuperDuper!, I actually let it Erase the destination (APFS-formatted) volume. So it will be "like old times" with CCC.

Thanks again. Definitely a relief that I have a viable alternative to SuperDuper! that actually works.

I don't think Jon's advice to allow CCC to erase is correct.

As far as I know, CCC must erase the destination volume the first time a new task is run in Big Sur, but after that it runs only incremental updates...at least that's the way my installation - Version 5.1.25-b4 (6153) - works.

Once I"ve run a task for the first time, my only options are Copy All Files (incremental update) and Copy Some Files; Full Volume Cone, which includes a mandatory erasure, ceases to be an option.

After a full clone, and if you want to run a full clone again, click New Task. That will give you all the options, including doing a full clone.

Now that you've forced me to think about it... If you erase with Disk Utility, you've got to reconfigure your CCC task, as opposed to configuring a new task as you've suggested.

Since both approaches get you to the exact same endpoint, I guess it comes down to which one you find to be personally less cumbersome.

Actually, the free version of Super Duper!, which offers only Full Volume Clone would be MartyByrde's best option (if it worked in Big Sur).

Agree 100%. Unfortunately, I did not get any indication at all from Dave as to when an updated version of SuperDuper! would be available. When OS 11.2 and a compatible version of Tech Tool Pro are released, and after doing some testing with both, I plan on making the move to Big Sur. Assuming SuperDuper! still has no newer version available, I'll download the free trial version of CCC and use it for 30 days. If SD comes out with a newer version during that time, I'll upgrade. If not, I'll just pay for CCC at that time.

Thanks, jchuzi.

After thinking my way through both options, I've decided that Jon's is the least cumbersome of the two.

That's the way I plan on doing it. And it's easier to do it "within" CCC.

TechToolPro 13.2 has been released, so feel free to take the plunge into Big Sur.

Actually, it is V13.0.2, but yes, getting closer. I have already downloaded it. Now just need to wait until OS 11.2 comes out, which should be very soon:

https://www.macrumors.com/2021/01/28/apple-seeds-macos-big-sur-11-2-rc-3/

Then after some testing, will make the move to CCC, and then completely to Big Sur, V11.2, on both of my Macs.

OK, V13.0,2 of Tech Tool Po works flawlessly with the latest version of Catalina, OS 10.15.7. Still waiting for OS 11.2 to be officially released.

I tried two things on my internal hard drive with Big Sur 11.1 and TTP 13.0.2. SMART worked fine but there was a problem with live verification testing Volume Structures. The test froze at 6:21 at Snapshot 16 of 32. I had to do a forced shutdown because everything was unresponsive. I notified Micromat about this and will report back with their response.

Previously, I had booted into Recovery Mode and run First Aid with Disk Utility. That went normally.

I use Tech Tool Pro for the following tests:

Memory Test
Smart Check
Partition Map
Volume Structures
Video Memory
Sensors Test
File Structures
Fans Test
(My Mac Book Air only) Battery Check

And for Tools:

Volume Rebuild

But I do all of them after restarting my Mac from Tech Tool Pro's eDrive. That avoids any issues.

However, not yet tested V13.0.2 with Big Sur, as I am waiting for V11.2, which should be out shortly. I'll then report back about testing TTPro, V13.0.2, with Big Sur, V11.2. I will still run the tests, and use the tTool, from the eDrive.

From Micromat's response, it looks like I should create an eDrive. Here is their reply:

Hello,

Thanks for the message. The only time a freezing should occur during a Check Computer suite of tests is while performing the Volume Structure testing. During the Volume Structures testing, to test a volume when it is the active startup-volume, the file system must be frozen. During this time, applications will be unresponsive. This is normal, and applications will become responsive again once the test has completed.

You might consider configuring a Check Computer suite of tests to run all other tests except the Volume Structure testing and then run the Volume Structure testing individually. The Volume Structures testing should take around 15 to 30 minutes to complete. If Volume Structure testing is still taking an excessive amount of time when running the Volume Structure testing individually, consider creating a Protogo device or eDrive and performing the testing while booted to one of those devices. The good thing about testing the Volume Structure’s of the internal drive from an eDrive or Protogo device, is the file system doesn’t have to be frozen in that setup, since you are booted to an alternative location other that the internal.

I believe there are more than one of the tests (and maybe Volume Rebuild also) that require running them from the eDrive. I have always used the eDrive for running the tasks I mentioned above, and never had an issue.

Well, OS 11.2 was just released. Have already downloaded the full installer file. I now have an afternoon project to do, after we get our COVID shots. Will be doing a clean, fresh installation of OS 11.2 on a partition of my external Samsung 1TB External SSD. I assume I can create a Tech Tool Pro eDrive of that partition, and thus can properly test Tech Tool Pro (along, of course, with my other apps, including the latest version of Onyx). As long as Apple did not throw any more wrenches or surprises, I expect testing to go well.

OK, just an update. So far, OS 11.2 is working well. And it seems faster. From my testing so far, the third party apps I have tested work fine, as well as Tech Tool Pro. Still no update yet for SuperDuper!. But as long as testing with Big Sur continues to go well, I plan on making the permanent move to V11.2 this weekend. And as I mentioned before, that will include the use of the trial version of CCC.

Well, Dave Nanian updated the Shirt Pocket blog:

https://www.shirt-pocket.com/blog/

Unfortunately, not a viable solution as far as I'm concerned. Bombich software has been able to come up with a more straight forward method for Intel-based Macs, and so it looks like I'll be moving to CCC.

Wonder what's going to happen with the next version of the Mac OS?

Two comments

1. Making a bootable external drive for an M1 Mac is doable, even easy, IF you use a high quality external SSD with a Thunderbolt 3 or 4 interface connected directly to one of the TB4 ports on the M1.
2. After numerous trials I have come to the conclusion that attempting to keep an external drive in synch with the internal drive by cloning only the data volume is a PITA for numerous reasons and although it might be faster to use a cloned data volume to recover than Time Machine either one is still a long tedious process with lots of steps. Unless and until Apple fixes the ASR routine and that routine successfully copies not only all the volumes including the security settings, I can't see cloning as a viable alternative. Of course YMMV.

IMHO, security issues will continue to put more bounds and constraints on macOS, its operations, and applications. The OS will become more of an unpenetratable black-box.

I have been contemplating replacing my mid 2018 Mac Book Air with an M1 model, but given all these hassles, I of course have resisted. Also, it's encouraging that Bombich software was able to resolve this "ASR" issue for Intel-based Macs, but very disappointing that Shirt Pocket Software has not.


With the way Apple has been developing recent versions of the Mac OS, I suspect you are correct. They sure don't believe in the KISS philosophy: Keep It Simple, Stupid. It seems Apple has a vendetta out for SuperDuper! and Carbon Copy Cloner!

Actually this is Apple's way of keeping it simple for the average user. Unfortunately making it more difficult for malware developers inevitably makes it more difficult for some utility developers and advanced users.

Nope, cannot agree. If Apple really wanted to, they could make it easier and clearer for the user, whether average or not. In actuality, something like that happened with V10.15.5 of Catalina. That release definitely created major pains for both SuperDuper! and Carbon Copy Cloner. Apple did get some what wise when that inexcusable snafu was corrected in V10.15.6, and continues in V10.15.7. Now with Big Sur, Apple seems to be sticking their noses up to both Shirt Pocket Software and Bombich Software. Definitely not good.

By-the-way, just when you thought it was safe to move to Big Sur macOS 11.3 is now in beta, just 24 hours after the public release of macIS 11.2.

Yeah, I saw that a little while ago. Most of its "features" are worthless to me, as 1) I do not use Safari at all (prefer Brave), and 2) I do not own an M1-based Mac. But there could be some useful security-related features that would be needed.

I will say, though, that everything is real solid with V11.2. As I mentioned before, it seems faster. Plus, one minor annoying bug I was having with V11.1 had to do with printing within Brave. But that could have been an application-related issue. In any event, that issue is gone.

Well, my "project" of installing V11.2 of Big Sur onto my Mac Mini did not go 100% as well as I expected, and I am actually back on Catalina. Here is what I did:

1. As usual, ran Onyx and Tech Tool Pro (V13.0.2, the latest one).
2. Did 2 SuperDuper! backups to my two separate Samsung 850 Pro 512 gig SSDs.
3. Restarted the Mini from one of those backups.
4, Used Disk Utility there (the version that comes with Catalina; may have some bearing on my issue that I'll mention below) to Erase and Format (as APFS) the 256 gig internal SSD inside the Mini.
5. Migrated to the latest version of the Big Sur installer, OS 11.2, and proceeded to do a fresh, clean installation of Big Sur onto that internal SSD.
6. At the completion of the installation, was offered, as usual, the ability to migrate files, folders, applications, settings, etc. from a choice of 3 sources. I (of course) chose the latest SuperDuper! backup that I had just completed, and as expected, all went well.
7. Restarted the Mini, and again as expected, started up without a hitch "into" V11.2 of Big Sur.
8. Granted Fill Disk Access to Onyx and Tech Tool Pro (along with some other system preference settings).

OK, so far, so good. Tested a few apps, and no issues. Launched Tech Tool Pro, and chose to create an eDrive. Once again, no issues with that. But when I selected "Restart eDrive", the eDrive did not show in my choice of startup devices. Only the one for OS 11.2. (I did verify that the eDrive had files on it). Tried again, but no go. When I restarted the Mini and held down the Option key, the eDrive did show up as a choice. After I selected it, the boot up process continued, but when it got to using the eDrive, could not do anything at all. Nada, Not a thing.

Checked the Micromat forums, and some folks were having an issue that they could not create the eDrive (seems most of them had to do with space issues, although not in all cases). Also, at least one person had the issue I had, ie, could not do anything with the eDrive. I have subsequently sent an EMail to the "help" area of Micromat, but with it being the weekend, of course am not expecting an answer right away.

When I first tried to "move" back to Catalina, and after re-starting the Mini from the SuperDuper! backup, I used Disk Utility there (again, version that comes with Catalina) to Erase and Format (as APFS) the internal SSD. But after doing a restore, etc., restarting the Mini (now on Catalina), launched Tech Tool Pro, but it would not let me create an eDrive, as there was not enough ?space? available. Even tried to do all that by doing a SuperDuper! restore. Same issue. What I finally did was a 3 step process:

1. Restart my Mac from my other external SSD that had Big Sur on it.
2. Launched Disk Utility from there to Erase and Format (as APFS) the internal SSD inside the Mini.
3. Followed Steps 3 through 8 above), except for step 5, migrated to the latest version of the Catalina installer, OS 10.15.7. And then of course for step 7, restarted the Mini into OS 10.15.7, ie, the latest version of Catalina.

All is well, and I was able to create the eDrive.

So, it seems there is at least one anomaly: to fully Erase and Format a drive that already has Big Sur on it, one must use the version of Disk Utility that comes with Big Sur (this has never happened to me before). Also, from previous versions of the Mac OS, I remember reading that when one does a clean fresh installation of the new Mac OS, it will first Erase and Format the drive one is trying to install the OS on. One question I have is that if the device has already been Erased and Formatted "properly" (ie, in the case of Catalina and Big Sur, formatted as APFS), when one launches the full installer, will it do another Erase and Format?

And the other unknown right now is the Disk Utility issue. Given that I erased and formatted the internal SSD with the Catalina version of Disk Utility, could that possibly be the reason why I could not create a usable eDrive? Will have to wait to hear from Micromat about that.

I have no experience with Big Sur on Intel Macs and there are definite differences, but from posts I have seen on other product support, web sites macOS 11.2 apparently broke some things associated with external boot drives that were working in 11.1. It appears the problem revolves around changes in the utility used to bless a boot drive. I have also seen reports similar to yours about the version of Disk Utility used to erase a volume. In both cases, early results indicate both issues are fixed in the current macOS 11.3 beta. Given macOS 11 is the biggest rework of Apple's OS since Mac OS X, you may have made the switch one update too soon. 🤷‍♂️

Bootable external drives on M1 Macs is altogether another matter given the sensitivity to drive type (SSD) and connection (Thunderbolt 3) and port (directly connected to either of the Thunderbolt 4 ports). I was hoping macOS 11.3 would have an update to the ASR utility for M1 Macs and therefore enable cloning, but no joy yet. 🙅‍♂️

Thanks for that excellent insight, joemikeb. Will be interesting to see what Micromat tells me. Also, will keep looking at the Tech Tool Pro forums. I just wish I had left OS 11.1 on my external Samsung SSD, installed Tech Tool Pro V13.0.2, and tried to create an eDrive.

Apple sure is making life more and more difficult. Issues with Disk Utility, and shutting out SuperDuper!, along with making hassles for CCC. And here we thought Windows was bad!

Any chance you are "allowed" to provide links to those sites? They could be both informative and useful.

OK, here is the reply I just received from Micromat regarding my eDrive issues:

"Thanks for the message. It sounds like the problem may be with the user that was active when the eDrive was created. This issue is quite common issue, especially when a user account has been migrated through multiple systems like a previous machine or earlier operating systems. To address this, one solution is to create a new admin user, and then log in as that user to create your eDrive. The reason we recommend creating a new admin user account and creating the eDrive from there is because it will utilize new ACL’s & Permissions and is a far simpler solution than the alternative of reseting the ACL’s on your account. (The New Admin User Account is just for the purpose of troubleshooting the eDrive creation failure.)

To create a new admin user open System Preferences and then select the Users & Groups preference pane (“Accounts" in 10.6 and earlier). Click the lock icon to unlock the preference pane so you can make changes. Next, click the plus icon at the bottom of the users column to create the new account. Change New Account from Standard to Administrator, and fill in a new username and password (It's ok to use the same password - makes it easier to remember.) Click Ok.

Once the new user has been created, log out (from the Apple menu) of you current user account and then log back in as the new user and open TechTool Pro from your Applications folder (you can skip signing into iCloud, etc.) Launch eDrive from the Mode menu and create a new eDrive partition, while logged into the new admin user account. Your new device will be based on the new user, so any time the eDrive requests a username and password, it will be the ones you just set up."

Sounds like a lot of work. I already responded to them, in that I am going to wait until V11.3 of Big Sur arrives before I try the move again. I also asked them if they are testing V13.0.2 of Tech Tool Pro with V11.3 (in beta) of Big Sur. I'll report on what they tell me.

By the way (forgot to mention this to Micromat), I've never had an issue regarding my User Account and making the eDrive. Seems like a strange excuse, but the way Apple has been doing things recently, who knows?

Looks like there is a newer version of Carbon Copy Cloner, V5.1.25, released on February 1st:

https://www.macupdate.com/app/mac/7032/carbon-copy-cloner

I assume this version works the same as V5.1.23 with Intel-based Macs, ie, one can backup/clone a Big Sur volume onto an external SSD as usual (no work arounds necessary).

jchuzi,

Would appreciate it if you could let us know if you are using the latest version of Carbon Copy Cloner, V5.1.25, that was released on February 1st, and that it works fine with Intel-based Macs and Big Sur. Sure would be helpful!

Yes and yes. All is well with that version of CCC, Intel, and Big Sur.

Thank you! That is definitely re-assuring! Now, as long as Tech Tool Pro "plays nicely" with V11.3 of Big Sur I'll be making the move.

Thanks again.

CarbonCopy Cloner Version 5.1.26-b4 (6173) successfully clones M1 Macs! I haven't stress tested it yet, and may not, but I am booted from a CC clone as I type this! 😎👏👍👌🌈✨💥

Does that version of CCC clone Big Sur on Intel Macs? By this, I mean the ability to clone the system, not just data.

Given:

• M1 Mac mini
• macOS 11.3 beta 5
• Carbon Copy Cloner ersion 5.1.26-b4 (6173)
• Sansung X5 500GB external drive (Thunderbolt 3)
• Connection via Thunderbolt 4 port on M1 Mac mini

Procedure:

1. Launch CCC
2. Source drive: Macintosh HD (internal drive on M1 Mac mini)
3. Target: Test (Samsung X5 SSD)
4. click Clone
5. Three options offered: Erase and clone, clone only the data volume, create a new volume on an APFS formatted drive and clone to it.
6. assuming the first option is chosen, acknowledge the drive will be erased and all data on it will be lost

Results:
😁 🙇🏻‍♂️ 👍 A bootable clone of Macintosh HD on Test. 👌⚡️ 👏

Observations:

1. I haven't tried the third option yet, but from experience, it should be possible to have multiple boot volumes on the same internal or external drive
2. The process overall is faster than a file-by-file clone (and it appears the data volume is a file-by-file copy) but significantly longer than ASR was in Catalina
3. I believe this is a macOS 11.3 beta 5 issue and have reported it as such, but System Preferences > Startup drive only shows the current boot drive as a startup option. To boot from the clone requires Shutting Down completely, Pressing and holding the power button until the message "Loading Startup Options" appears and selecting the boot drive there.
4. Beats h3🏒🏑 out of cloning the data volume and then installing the OS.

FWIW, I can only get up to CCC 5.1.25 on the Bombich website.....is your 5.1.26 version a beta?

Carbon Copy Cloner 5.1.26-b4 is the fourth beta release of 5.1.26. It is available via CCC > Preferences > Software update and checking the box labeled "inform me of beta releases".

TESTING UPDATE

I cloned my system to an SSD connected via USB 3.1 gen 2, the data transfer rate was roughly 10% of what I see installing to a Thunderbolt 3 SSD.

RESULTS:

2 out of 2 attempts at the conclusion of the clone procedure, Big Sur popped up a warning the data volume had been improperly disconnected and when I attempted to boot from the drive I received a "validation error." The same error I get from Thunderbolt SSDs that are not directly connected to one of the Thunderbolt 4 ports on the M1 Mac mini.

CONCLUSION:

Bootable external SSDs must be directly connected to either of the two Thunderbolt 4 ports on M1 Macs.

LATEST RESULTS:

CONFIGURATION:
M1 Mac mini with Samsung X5 1TB SSD attached directly to one of the two Thunderbolt 4 ports using an OWC Thunderbolt 3 cable, macOS 11.3 beta 5 (20E5224a), CCC Version 5.1.26-b4 (6173).

ISSUES:

1. The clones are not exact clones of the source drive. There are kernel extensions, notably SoftRAID 6.0.1, installed on the source drive. The SoftRAID kernel extension is not installed in the clone although it does appear in /Library/StagedExtensions
2. In order to install a kernel extension it is necessary to set the Security Policy for that particular volume. When I attempt to do that on the clone the system reports “No Administrator Was Found” and does not change the Security Policy for that boot volume. Therefore it is impossible to induce the kernel extension to install.
3. This one is harder to nail down, but if I leave the cloned drive connected and the computer booted from the source drive I am encountering random system crashes. These crashes typically occur overnight and it appears to happen whether the clone volume is mounted or not.
4. The clone does not appear in System Preferences > Startup Drive, but it does appear as a Startup option.

REALITY CHECK:

I installed macOS 11.3 beta 5 on a second Samsung x5 SSD, and…

• It appears in System Preferences > Startup Drive
• I successfully changed its security policy
• It was mounted overnight and there was no System crash
• I have not attempted to install the SoftRAID kernel extension yet

CAVEAT:

I am fully aware many, even all, of these issues may be in Apples domain, so I have submitted trouble reports to both Apple and Mike Bombich.

I have had a thought about the overnight crashes: The Samsung X5 used for the clone is a 1TB model and appears to get a lot hotter than the 500GB model I installed to, so heat in the drive is a potential suspect. I wish I could afford this OWC drive to compare against. The Samsung is in a solid plastic case with no apparent heat sink or cooling and they get WARM, where OWC's enclosure is all heat sink. But that will have to wait until my birthday or Christmas.

TALK ABOUT A RESPONSIVE DEVELOPER‼️

I received Mike Bombich's response to my problem report less than 24 hours after sending it. I thought I would share his response with FineTunedMac.

1. The clones are not exact clones of the source drive. There are kernel extensions, notably SoftRAID 6.0.1, installed on the source drive. The SoftRAID kernel extension is not installed in the clone although it does appear in /Library/StagedExtensions
   
   Originally Posted by Mike Bombich

   At the end of the procedure, it's impossible for the volumes to not be identical. Immediately following the clone, however, Apple's APFS replication utility calls upon the bless utility to "personalize" the OS on the destination. This involves code signing the kernel extension cache using a machine-specific identifier stored in the M1's security enclave, and possibly rebuilding the kernel cache (given your observations, I suspect the kernel cache must have been rebuilt). I can't have any influence on this part of the procedure, Apple has wrested control of this from every third-party.
2. In order to install a kernel extension it is necessary to set the Security Policy for that particular volume. When I attempt to do that on the clone the system reports “No Administrator Was Found” and does not change the Security Policy for that boot volume. Therefore it is impossible to induce the kernel extension to install.
   
   Originally Posted by Mike Bombich

   If you attempt to boot from the volume, you should be prompted to grant administrator rights to one of the users on that volume.
3. This one is harder to nail down, but if I leave the cloned drive connected and the computer booted from the source drive I am encountering random system crashes. These crashes typically occur overnight and it appears to happen whether the clone volume is mounted or not.
   
   Originally Posted by Mike Bimbich

   It could be an overheating issue, but I think it's more likely that these are simply bugs in the "External Boot" solution that Apple hasn't sorted out yet. We were already seeing a lot of issues when people were simply installing macOS onto external devices (specific to M1 Macs, not too many issues on Intel Macs).
4. The clone does not appear in System Preferences > Startup Drive, but it does appear as a Startup option.

IN CONCLUSION


At least cloning works albeit it is not fully effective, and limits the usefulness of a clone as a backup alternative. There are a few more tests I want to conduct…

• I have seen the prompt Mike mentioned to grant administrator rights, but it has not bee consistent
• If I grant administrator rights on a clone, can I then change the volume Security Policy?
• If I can change the volume Security Policy, can I successfully install kernel Extensions
• If I get all that working can I clone back to the internal drive without going through a lot of rigamarole?

All of this and I wasn't that much of a fan of clones to start with. 🙄 FWIW I still rely on Time Machine as my primary backup which is why I was so anxious to get the SoftRAID drivers working.

MORE CLONE TESTING

TEST OBJECTIVE: To determine any further limitations to bootable clones and determine the true usefulness of a boot drive clone.

TEST SYSTEM CONFIGURATION:

• M1 Mac mini, 16 GB memory, 500 GB Storage
• MacOS 11.3 beta 5 (or 6 -- I have lost count)
• Carbon Copy Cloner Version 5.1.26-b4 (6173)
• Samsung X5 1TB Thunderbolt 3 SSD Samsung X5 500GB Thunderbolt 3 SSD

FINDINGS:

• The only way to create a bootable clone requires allowing ASR to erase the target drive.
• The System volume cannot be updated by any method and remain bootable.
• Kernel Extensions -- as opposed to user extensions -- do not clone and have to be installed after cloning
• The source volume security settings are not included in the clone, which inhibits installation of kernel extensions
• I have been unsuccessful in all attempts to change the security settings of a cloned volume but I can easily change the security settings of an external drive that was created by the installer.
• No matter how the external boot drive is created, whether by cloning or intalling the OS, the first time it is booted, all of the applications will be verified. (Given the 490,000+ files/items/objects in Xcode, it can take an annoyingly long time to verify just by itself).
• Running a CCC clone to a previously cloned volume works (in this case CCC only clones the data volume), but all the applications must be re-verified the next time you boot from the volume
• Apple's new 1 True Recovery Volume in macOS 11 (Big Sur) is a major improvement.
• Compare volume structure of the internal drive with that of the cloned drive and a installed drive and you will see there are two containers (APFS partitions) iBootSystemContainer and RecoveryOSContainer, on the internal drive that do not appear on either of the external drives. Obviously the internal drive provides functionality that is not available on either of the external drives. I cannot verify this, but I have read that without these present in the system, the system is not bootable. (NOTE: this needs to be tested with a full macOS 11.3 installer when it is released, the results may be different.)
• The Data volume on mounted external drives tend to unexpectedly dismount when not in use.

CONCLUSIONS:

1. Bootable external Thunderbolt 3 or 4 SSDs are possible in macOS 11 M1 Macs running Big Sur.
2. Those can be created either by installing or cloning from the internal drive.
3. Any loss of contact with the "iBootSystemContainer" in the internal drive will render the system unbootable from any drive (this can be restored, but the process require using a second M1 Mac.)
4. Clones are less functional than external drives created by installing from the Recovery Assistant, due to kernel extension and security policy issues.
5. Bootable external boot drives are not as useful as they were in previous versions of macOS, but they are still viable.

FWIW — MY PERSONAL CHOICES:

• Time Machine together with Apple's 1 True Recovery Drive remain my primary backup and disaster recovery tool set
• I will continue to keep a copy of the latest full installer on a bootable thumb drive for deep disaster recovery purposes
• For testing purposes I will install macOS on external drives rather than use clones because of limitations in clones.
• I will continue to clone my data volume on the theory that in the event of a disaster, recovery might be faster than using Time Machine.
• I remain eager to see Mike Bombich's "exciting new features" in Carbon Copy Cloner.