See here:
Creating legacy bootable backups of macOS Big Sur (and later OSes)
Stephen
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Ok. So bootable backups not quite possible. Got that.
As the article says, it can be done with CCC but:
We also do not generally recommend that users attempt to make their backups bootable — you can restore all of your documents, compatible applications, and settings from a standard CCC backup without the extra effort involved in establishing and maintaining a bootable device.
I decided, some time ago when still using macOS Big Sur, to abandon bootable backups following that advice. Personally, I have not lost sleep worrying about that.
Stephen
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Sounds like you use CCC and use their standard backup as one backup. Am I right?
In that case, does CCC copy the whole Devonthink Database package when it backs up or does CCC only copy files that are changed from inside the package?
Like Time Machine and Arq, CCC only copies the changes. My CCC backups usually take less than 5 minutes.
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I confirm what @chrk said: only the changes are copied. I connect an SSD to my MacBook Pro every night which initiates the CCC backup and the backup almost invariably takes a couple of minutes (with the SSD automatically ejected at the end). It’s very fast.
Stephen
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I’m backing up 
@chrk and @Stephen_C on the speed of CCC. My backup runs at 9pm every night and it usually less than 10 min for a backup to run.
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Thank you for sharing your experience.
I need to figure out if Chronosync can do this (since I already have the software), and if not, then it may be worth purchasing an upgrade for my older CCC license.
Do you use CCC for local network backup also (either a NAS or as in my case hard drive connected to a Mac mini on local network)?
Have a wonderful weekend.
in this long thread, I’ve lost track of what “this” is.
If you can mean can Chronosync backup the DEVONthink backup zip files, yes it can.
If you mean can Chronsync backup open DEVONthink package folders … not reliably, nor can anything probably, since DEVONthing is working on the collection of files in the package files while copying. If the databases closed, then yes Chronsync like any other file copy program can work.
Or am I missing something?
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From my experience, I’d honestly say an upgrade to the CCC license is warranted.
Currently I only use it for a local connected external but that’s because my NAS and some of my subnet are in flux while I’m building something).
You and yours have a great weekend too!
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by I need to figure out if Chronosync can do this I meant whether Chronosync can copy only the changes as CCC appears to be able to do successfully.
Also are you suggesting that when you backup using CCC, you quit Devonthink while the backup is going on. Quitting Devonthink during backup does make sense to me - especially if CCC is backing up the Devonthink package files.
I don’t think that applies to Snapshot based backup apps like Time Machine, CCC and Arq.
I have never closed a database and all 3 three apps constantly back up while I’m changing things in Devonthink and other apps.
This is in line with their documentation.
From Arq…
From CCC…
The only requisite seems to be APFS, but that’s has been the default for some time now with Apple. You can’t even create encrypted HFS+ volumes any more or use HFS+ for Time Machine.
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There is no need for this with Time Machine, Arq or CCC*.
*If you use a destination volume for CCC that has an older file system, I would contact the CCC dev first or search through the knowledge base.
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I’m suggesting that … but maybe I’m wrong. Experts here with whom I defer.
I believe not an issue with TimeMachine (per the DEVONthink documentation). Hence I feel more than covered using TimeMachine as primary for EVERYTHING, and use Chronsync to move the very important stuff, like a few DEVONthink Zip files. I keep it simple and try not to get too many software licenses. Just me.
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It’s not a bad idea and I know @cgrunenberg generally suggests it.
DEVONthink isn’t closed when my backups roll but they’re scheduled at a time when I’m usually not actively working in DEVONthink or DEVONthink To Go, i.e., no active would be happening either.
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Thank you for sharing.
I suppose at the OS level, snapshot copies of all files are stored for the backup process and retained until the backup process completes its job. I guess it is possible, but if it is a large file or large number of files that are being modified during backup, that much extra space will be used up on the drive in the interim, but the OS likely knows how to do this when requested by these backup processes.
Thank you for all your replies. Backup if you want to do it right, can be complicated by itself. 
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You’re welcome.
Snapshots are read-only frozen in time backups. I have started Arq and CCC backups in the past and started to delete files from within DEVONthink and a test database itself while the backups were running.
They were fine and not affected by the deletions.
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ooh. that is the kind of proof which inspires confidence. thank you for sharing!
so it does seem that these processes are able to ask the operating system to hold “read-only frozen in time” for the process to access and when the process is done, it presumably has to ask the operating system to let go of that “read only snapshot”.
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Yes, CCC help states that it removes the temporary read-only source snapshot at the end of the backup task (see screenshot above).
You could even keep the source snapshot on the local volume, there is a setting in CCC for that if want to.
Time Machine itself does this by default (for a day or so).
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Good stuff and good to know. Thank you for sharing.
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