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Carbon Copy Cloner 7 - Users Thread
- Thread starter Realityck
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Restoring a mac: Snapshots vs Migration Assistant
I am not a computer person, so I am not sure my opinion is correct or just trivial or common knowledge.
I understood snapshot wrong. I thought files on the Macintosh HD were locked by the CCC snapshots. This is obviously wrong, as proven by the following experiments.
It is well-known that one can use a snapshot to restore to a previous state of the mac. However, restoring a new or newly installed mac, one generally uses Migration Assistant. I found that this need not be the case.
1) I have Sonoma 14.7 on my mac(1) and have enabled snapshot support (hourly) on CCC7’s backup disk for about a year.
I reinstalled Sonoma 14.7 on another mac(2) and found that I could restore it using the latest snapshots of mac(1), such that mac(2)=mac(1). This suggests that a (or any) CCC snapshot can restore a mac with the same OS.
Of course, I had to install CCC on the newly installed mac(2) in order to use CCC snapshots.
2) I then erased mac(2) and installed Sequoia 15.2 on it. Similarly, I restored it using the latest snapshots of mac(1), such that mac(2)=mac(1). This suggests that a (or any) CCC snapshot can restore a mac with a newer OS.
Thus, for restore, snapshots can be an alternative to Migration Assistant; they give the same result.
I prefer using snapshots because CCC makes snapshots so simple to use and requires fewer steps than Migration Assistant. Unless it is a fresh install, Migration Assistant sometimes creates two sets of users, one set from the original mac and another set of users from the source used for migration. I had spent a lot of time trying to delete the first set of users and had little success.
When using CCC as the source, Migration Assistant only allows the latest CCC backup as the source, but not a snapshot of any date. According to CCC, it is Apple that prevents the use of a desired snapshot. It said a workaround is to restore the desired snapshot to an empty drive, then use the drive as a source in Migration Assistant. This should work as proven above. But it is also not necessary also proven above.
I am not a computer person, so I am not sure my opinion is correct or just trivial or common knowledge.
I understood snapshot wrong. I thought files on the Macintosh HD were locked by the CCC snapshots. This is obviously wrong, as proven by the following experiments.
It is well-known that one can use a snapshot to restore to a previous state of the mac. However, restoring a new or newly installed mac, one generally uses Migration Assistant. I found that this need not be the case.
1) I have Sonoma 14.7 on my mac(1) and have enabled snapshot support (hourly) on CCC7’s backup disk for about a year.
I reinstalled Sonoma 14.7 on another mac(2) and found that I could restore it using the latest snapshots of mac(1), such that mac(2)=mac(1). This suggests that a (or any) CCC snapshot can restore a mac with the same OS.
Of course, I had to install CCC on the newly installed mac(2) in order to use CCC snapshots.
2) I then erased mac(2) and installed Sequoia 15.2 on it. Similarly, I restored it using the latest snapshots of mac(1), such that mac(2)=mac(1). This suggests that a (or any) CCC snapshot can restore a mac with a newer OS.
Thus, for restore, snapshots can be an alternative to Migration Assistant; they give the same result.
I prefer using snapshots because CCC makes snapshots so simple to use and requires fewer steps than Migration Assistant. Unless it is a fresh install, Migration Assistant sometimes creates two sets of users, one set from the original mac and another set of users from the source used for migration. I had spent a lot of time trying to delete the first set of users and had little success.
When using CCC as the source, Migration Assistant only allows the latest CCC backup as the source, but not a snapshot of any date. According to CCC, it is Apple that prevents the use of a desired snapshot. It said a workaround is to restore the desired snapshot to an empty drive, then use the drive as a source in Migration Assistant. This should work as proven above. But it is also not necessary also proven above.
If you didn't post and kind enough to show me how, I would not have known how to do it. So I remembered as Lou's method.
Its was posted very early in this thread. It hasn't change much, except for issues with Apple's APFS replication utility that crop up infrequently until resolved. That doesn't effect a standard data volume backup only legacy 4 volume snapshot copy.
I have a questions for you both, experts on this topic.
Suppose I had a CCC bootable backup. My mac is corrupted. Could I boot from the CCC bootable backup and restore both the system and data volume? Or I need to reinstall the OS first?
Am I correct that the CCC bootable backup could be make at anytime during the use of CCC and does not have to be the first ever backup.
If the legacy bootable copy works, you would boot from the volume, and then run CCC restore and overwrite corrupted Mac volume set. Alternatively you can just use the CCC snapshot or any ext ASR volume to restore settings/apps/data after clean reinstall of MacOS via Migration assistant.
You actually rarely encounter disk corruption with SSD drives, so frequently people just have the Apple store staff use Apple Configurator running on a another AS Mac Laptop with recommended hookup to execute a DFU restore (wipe all, fresh MacOS and system FW), then restore everything using migration assistant with ASR volume connected to a correct USB-C port . Yes there are specific instructions for that which is different depending on Mac
Legacy bootable backup are a snapshot that remains unchanged until you overwrite it with a new snapshot. Because I mentioned unchanged its not a backup you can archive to. That is the role of a standard backup that you can backup or active to.
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Thank you for taking the time to explain!
Also, wondering what do you mean “backup you can archive to”. I thought each time when CCC does a backup, it update the previous backup. However, there is only one backup on the disk, the previous backup is erased and is not archived.
I read your reply several times and carefully. Don’t understand the above. “remains unchanged until you overwrite it with a new snapshot.” do you mean “remains unchanged until you overwrite it with a new LEGACY BOOTALBLE BACKUP snapshot.”?
Also, wondering what do you mean “backup you can archive to”. I thought each time when CCC does a backup, it update the previous backup. However, there is only one backup on the disk, the previous backup is erased and is not archived.
Yes a legacy snapshot is a one time process that you can’t update the system or data afterwards per developer like a standard data volume only backup. That’s why I said until you overwrite everything.
Sup flowrider. Have a great Sunday.
Anyhow I just finished a project on Pro Tools, and finally ready to upgrade to Sequoia.
Have Monterey, Sonoma (running now) on the same NVMe and getting ready to create another container.
Any preemptive suggestions?
Also thank you and the rest in the past for keep me chugging along.😉
I continue to explore CCC Legacy Bootable backup. Suddenly, it didn’t work any more, failed by “missing backup disk”. I checked, it turned out that I was using OS14.7. It seems that at present, only 15.2 can produce a bootable CCC backup.
Also CCC says that even a successful bootable backup is generated, further backups on this drive will make it non-bootable. Just wondering if you have done further backups to see if this saying is true.
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Are you following this discussion about macOS 15.2 https://discussions.apple.com/thread/255886342?sortBy=rank
I suggest you just give up on bootable clones, except for one off activities like a few migration scenarios. As part of a regular backup schedule, they now serve little purpose except perhaps for pre-T2 Intel Macs.
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As I mentioned before, legacy bootable snapshots are a one-time deal. Want to update the snapshot? You overwrite it. There is no daily backup or archive activity with a "legacy snapshot".
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So sorry, I don’t have the intelligence to understand you previously. But when you emphasized it again I believe I understand more this time.
My understanding of a bootable backup is, I could boot from it, modify a word doc and save the changed doc. Next time when I boot, the changed file will be there. There is no difference than working on a Mac.
When you said a bootable clone was a snapshot. I interpret it as like a regular CCC snapshot, I could restore from it, but can not make any change to it. Yes?
Gilby101, your knowledge is broad and knows such thread exists! Thanks for sharing! I read that thread, now I know many minds have been consumed by bootable clone and is unwise for me to spend time on it. It seems that the preferred way of doing is:
“install the OS from Recovery mode. When it gets to the end and asks if you have data to restore, you point it to your CCC backup. All of that gets merged in and you have an exact replica of your backup, which is also bootable.” (post by Kurt Lang.) I believe this is also the way recommended by CCC.
I still somewhat perplexed:
1) why before apple sealed the system volume, bootable clone was desired and why now it’s value has waned?
2) I have two macs. if the one I am working on everyday is suddenly dead, if I have a bootable clone, could I not just use CCC to mirror the entire system to the spare Mac or a new Mac? Will this of value?
But the view in (2) is wrong, correct? According to Realityck, a bootable clone is a snapshot frozen in time sometime in the past and it won’t have the latest changes whereas a standard backup is far more valuable as it has the latest changes.
Bootable clones are now seen by Apple as a potential security risk. Hence the need to make changes in recovery mode before booting from an external disk on an Apple silicon Mac. Bootable clones are also of less value now that booting an external disk requires a working internal disk. I would say that there now fewer disaster scenarios where bootable clones are useful.
There is some value of a bootable clone in the two Mac situation though it is not easy to make reliable and maintain it as reliable. Obviously it needs to be recreated at frequent intervals (e.g. daily so long as you accept the loss of changes since the backup). This is only if minimising recovery time is an essential requirement.
But this is all very cumbersome and requires frequent testing to be sure that it will work when needed.
I think you are taking a tool (in this case CCC) and forcing it to fit scenarios where there may be better solutions. For example:
If I had disaster requirements of continuous operation, I would use two identical Macs. Keep them at the same macOS and application versions and synchronise data between the two. Data synchronisation could be scheduled (e.g. using ChronoSync) or real time (using Resilio Sync). This is, of course, in addition to normal backup requirements to external SSD.
In practice, I use Resilio Sync and Chonosync to keep "essential" data synchronised between my 2019 iMac and my 2023 MBP. As well as satisfying some disaster recovery needs, it provides for ease of normal use between the two Macs. For me the "essential" data is all my documents and PDFs along with Lightroom catalog and a subset of my photos.
Yes, that is the straight forward (and well tested) way to recover.
Gilby101, thanks for explaining the need for a bootable drive in a way that non-technicals can understand!
My biggest misunderstanding is that I thought CCC bootable clone means a CCC standard backup which is also bootable and functions like having another Mac with all the current files when it is booted. But after you, Realityck explaination, now I understand it is only booted to a state in the past and that no more backups can be put on it after its creation.
It seems like a good idea to use the old Mac as a spare replica of a newer Mac. Can sync takes place over WiFi between the older Mac left at home and the newer Mac stayed in the office? What is the main difference between ChronoSync and Resillo Sync? If the Mac has 1TB of data, is it still doable?
My biggest misunderstanding is that I thought CCC bootable clone means a CCC standard backup which is also bootable and functions like having another Mac with all the current files when it is booted. But after you, Realityck explaination, now I understand it is only booted to a state in the past and that no more backups can be put on it after its creation.
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Gilby101, have been thinking what you said:
When disaster strikes, the new Mac is dead. Then I just boot the old Mac, restore it using the latest snapshot. This will take very little time like less than 1/2 hour for the old Mac to function as if it was the new Mac. This will avoid the trouble of maintaining two macs to keep them sync, which probably not trivial nor non-technicals. The probability of all 4 backups are ruined is small.
Just wondering what ur thought is.
Another alternative is just don’t get rid of the old Mac. Installed on this Mac, the same OS of the new Mac. Do the 321 like you had suggested: 1 TM and 1 CCC backups at home and at work and ARQ backup of the home folder on cloud.
When disaster strikes, the new Mac is dead. Then I just boot the old Mac, restore it using the latest snapshot. This will take very little time like less than 1/2 hour for the old Mac to function as if it was the new Mac. This will avoid the trouble of maintaining two macs to keep them sync, which probably not trivial nor non-technicals. The probability of all 4 backups are ruined is small.
Just wondering what ur thought is.
Lou,
From your post, bootable clones have high values. Yes?
May I ask what are the other two boot discs? Why so many?
“You boot to another bootable disc and recover.” —- how does one recover from the boot disc that is bad?
Also beside boot discs, wondering if you are doing regular backups.
With Apple silicon, the Mac requires the internal disk during the boot sequence. So no working internal disk, no booting from anything. Recovery depends on exactly what is wrong with the internal disk.
All depends on your exact needs. Some people may need to have another Mac in the office with them because they can't function (make money or whatever) without a computer. You may well be happy with two different Macs in different locations.
Chronosync can synchronise folders on one computer or over a LAN. In principle it could do so over the Internet, but would need a network layer like Tailscale.
Resilio Sync is designed to sync over the Internet as well as locally.
Chronosync is well supported, Resilio Sync less so unless you are a higher paying enterprise customer.
But we are straying from the topic of this thread. Let's leave it at that.
I've found that... now and then... it is STILL useful to have an external bootable drive.
However... it doesn't HAVE to be "a clone". It can just be an external drive that's bootable.
It's still possible to create such drives.
FOR NOW.
I'm wondering if at some point in the future, Apple will "take away" the ability to create ANY kind of externally-bootable drive.
Hmmm...
Is it possible to boot an iPad from an external drive?
I have NO experience with iOS -- but I'm thinking that Apple is slowly but inexhorably "transforming" the "Mac OS" into a new "Mac iOS" ...
However... it doesn't HAVE to be "a clone". It can just be an external drive that's bootable.
It's still possible to create such drives.
FOR NOW.
I'm wondering if at some point in the future, Apple will "take away" the ability to create ANY kind of externally-bootable drive.
Hmmm...
Is it possible to boot an iPad from an external drive?
I have NO experience with iOS -- but I'm thinking that Apple is slowly but inexhorably "transforming" the "Mac OS" into a new "Mac iOS" ...
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As posted, I have four boot discs. Two are for Sequoia (a working disk and a backup clone of the last released update that worked), and the other two are for Sonoma, should I ever have to revert to an older OS.
If my boot disk catastrophically fails, I can boot to the backup, erase the damaged boot, and clone the backup to the erased disk, and I'll be ready to go.
Note - I update my working disk with betas and if a beta causes an issue, I have the backup.
Lou
Lou, I can see you are a very careful person who thought of all disastrous scenarios and everything has two copies. Just wondering if you do backups regularly as well.