Why can't I copy my Time Machine Backup to an External (Case-Sensitive) drive?

[peacockharris]

I'm currently using an old iMac while my newer Mac is off for repair, and have come across an issue I never have before.

When attempting to back up a copy of my newer Mac's 'APFS (Case Sensitive)' Time Machine to my new backup drive (8TB to hold many other backups, not just Time Machine) it came up with an error that the volume had the wrong case sensitivity for backup. The Target drive was formatted as regular old 'Mac OS Extended (Journaled)'

A quick Google search later, and it seemed I just needed to format the new drive as 'Case Sensitive' too, and that would give it the flexibility to work with both 'Case-Sensitive' and 'Case-Insensitive' volumes. It was reformatted as 'Mac OS Extended (Case-sensitive, Journaled)', as APFS isn't currently an option on this machine running Sierra.

Job done, or so I thought.

I then tried copying the Time Machine backup for this older machine, and was faced with the same error about case sensitivity. I'm confused, because supposedly having my new backup drive formatted as 'Case-Sensitive' covers all options. The Time Machine backup in question shows up as neither 'Case-Sensitive' nor 'Case-Insensitive'. It just says 'Mac OS Extended (Journaled)'

This new drive has accepted transfers from drives formatted as 'APFS Case-Sensitive', 'APFS Case-Insensitive', and also a clone of the main HD (Macintosh HD) which was 'Mac OS Extended (Journaled)'.

However this particular Time Machine backup brings up this error that didn't apply to another drive with the exact same formatting.

This makes no sense to me. Does it make sense to anyone else?

 

[MacInWin]

The newer backups cannot be processed as if they were "normal" files. That is because they are NOT normal files, but TimeMachine backups. And although normal files can be copied from APFS to HFS+ drives, TM backups cannot. So, yes, it makes perfect sense.

Why are you trying to do this? Messing with a good backup is an excellent way to destroy it. TimeMachine does many things in the backup, including file compression, replacing files with tokens if not changed, etc. Just love it alone until your repaired Mac returns.

 

[peacockharris]

I think you misunderstand....my Time Machine for my newer Mac (APFS, case sensitive) transferred fine to the HFS drive. Clearly Time Machine backups *can* be copied, contrary to your reply, and I've always done so the entire time I've owned Macs for extra peace of mind. With respect, I'm not "messing" with anything. I'm not altering the TM backup, I'm simply duplicating it. I've also restored my system from some of these duplicated TM backups in the past, when the actual time machine backups have become corrupted or given errors. So I don't think creating a backup of my backups is without merit. But I digress...

It's the attempt to copy the HFS Time Machine to a HFS drive that's spitting out the erroneous error about case sensitivity. And it doesn't seem to make sense, as there is no apparent case sensitivity incompatibility between the two drives. That's what I hoped for an explanation on.

 

[MacInWin]

OK, read this:

Copying a Mac volume to another file system (and back)

Tired of HFS+? Disenchanted by APFS? Why not copy or back up to a different file system? Here are crocodiles waiting to bite you.

eclecticlight.co

and then this:

The trouble with snapshots: how can you copy them?

Until Big Sur started backing up to snapshots on APFS, there was little interest in being able to copy snapshots. Now we realise that we can’t.

eclecticlight.co

It is not as simple as you think.

But good luck with it.

EDITED: To put in a correct link.

 

[peacockharris]

Regardless of what I may not be taking account of in making my copies (and they have saved me in the past, regardless). This still doesn't answer my question.

Why would a drive that is 'Mac OS Extended Journaled' copy with zero issues, whereas another 'Mac OS Extended Journaled' drive spits out an error about case-sensitivity when there is no such incompatibility?

Perhaps I shouldn't have even mentioned it's a Time Machine backup, as that's become the focus when it wasn't my question.

 

[MacInWin]

Given how quickly you responded, I take it you didn't read either article. They talk about copying from different system formats.

 

[peacockharris]

I'm copying from and to the same format.

'Mac OS Extended Journaled' to 'Mac OS Extended case-sensitive, Journaled'

I wasn't aware the addition of case sensitivity made them different formats. I was under the impression making the target drive 'case-sensitive' facilitated transfer from both 'case-sensitive' and 'case-insensitive' drives.

 

[MacInWin]

I wasn't aware the addition of case sensitivity made them different formats.

They are.

 

[peacockharris]

Ok. I stand corrected. I considered them variants if anything...

Still, it's a mystery why one 'Mac OS Extended Journaled' would copy fine, and the other 'Mac OS Extended Journaled' would throw out that *specific* error.

 

[MacInWin]

Can you help with some clarity? You said this, which addressed copying a backup from APFS to HFS+.

When attempting to back up a copy of my newer Mac's 'APFS (Case Sensitive)' Time Machine to my new backup drive (8TB to hold many other backups, not just Time Machine) it came up with an error that the volume had the wrong case sensitivity for backup. The Target drive was formatted as regular old 'Mac OS Extended (Journaled)'

Then you said

I then tried copying the Time Machine backup for this older machine, and was faced with the same error about case sensitivity.

And then

It's the attempt to copy the HFS Time Machine to a HFS drive that's spitting out the erroneous error about case sensitivity.

and finally

Perhaps I shouldn't have even mentioned it's a Time Machine backup, as that's become the focus when it wasn't my question.

So, are we talking about trying to copy a TM backup or not? There are many other factors in trying to copy a TM backup, beyond just case sensitivity. APFS, by default, compresses files into sparse files to economize on disk usage, but then when you copy from that source to a non-APFS destination, that compression has to be undone, for example. And TM backups of more modern systems are now snapshot format, which adds further compression. But when trying to copy that snapshot from an APFS drive to one that doesn't support compression (HFS+), then all of the compression needs to be undone.

Generally, it is not a good idea to attempt to copy a TM backup snapshot from APFS to anything else.

Finally, it is best not to mix backups on the same drive, as you say you are doing on the 8TB drive. TM now takes over the drive totally, restricting what can be done to the drive, to protect the integrity of the snapshots and sparsebundle files it creates. So, although in the past it may have been acceptable, with more modern versions of macOS it is NOT recommended to mix things on the backup drive. It is far better to get a smaller drive and dedicate it to the TM backups and let TM manage the drive totally.

 

[peacockharris]

Yes, both fails involved the TM backups (when the target drive was formatted differently both times. 'Mac OS Extended Journaled' the first time, and
'Mac OS Extended case-sensitive Journaled' the second time. I can confirm this.

(The APFS volume I tried copying first was subsequently successfully copied upon the reformatting of the target drive, to 'Case Sensitive'. In that instance, it gave me an error, I corrected specifically for that error, and it gave me a successful copy. However this does not explain the subsequent error with the other drive).

In your final explanation you say "There are many other factors in trying to copy a TM backup, beyond just case sensitivity." and then go onto talk about compression and whatnot.

Informative as this may me, what does any of this have to do with answering my question about why this particular 'Case Sensitivity'? error *is* what pops up? (which is what I've been curious about finding an explanation for this entire thread)

If you don't know, that's fine. I'll still take your advice on best practices on board.

I note you talking about your advice applying more to 'more modern' versions of OSX. Not sure how new you mean, but this is taking place on Sierra, hence the lack of APFS option on the target drive. If that helps clarify.

 

[MacInWin]

Sierra actually can address APFS. In fact, APFS was introduced with Sierra.

Can you say what tool you used to make these transfers?

This new drive has accepted transfers from drives formatted as 'APFS Case-Sensitive', 'APFS Case-Insensitive', and also a clone of the main HD (Macintosh HD) which was 'Mac OS Extended (Journaled)'.

If you used TM, then TM handled the transitions for you behind the scenes. If you used a cloner software (CCC or SD!), then it handled the issue. (You mentioned "clone," so that was why I thought of those two applications.)

Frankly, I think the error message is just wrong and that the system cannot handle transferring your old TM format to a new format drive.

You can test that by creating a non-TM file on the old drive and see if it will copy to the new. If it does, then the error is that you are trying to move a TM backup outside TM. If it throws up the same error, then I have no idea why that should be, to be honest, other than Sierra is very old and may not have the latest tweaks to the APFS file structure as Apple has tuned it.

 

[peacockharris]

Pretty sure APFS was introduced in High Sierra, not Sierra. I have no such format option on my system.

Yes, Superduper was used to create a clone drive, and then that was dragged and dropped again to this larger backup drive to provide added redundancy.

Based on your helpful advice, I may well forego copying Time Machine backups directly in future and instead opt for straightforward clones of the system drive instead (though this eliminates the 'Time Machine' aspect I've found useful in the past, should my actual TM drive/s fail).

Thanks.

 

[MacInWin]

Pretty sure APFS was introduced in High Sierra, not Sierra. I have no such format option on my system.

Apple File System - Wikipedia

en.wikipedia.org

It was limited in usability, but Sierra could use APFS. High Sierra really did introduce it fully. Read the paragraph under "support" in that article for more detail. I guess it depends on the definition of "introduced." No big deal, though.

Based on your helpful advice, I may well forego copying Time Machine backups directly in future and instead opt for straightforward clones of the system drive instead (though this eliminates the 'Time Machine' aspect I've found useful in the past, should my actual TM drive/s fail).

I would go the other way myself. You have two Intel machines and are not yet running Ventura, so booting from an external drive is handy. But once you move to Ventura, or get an Apple Silicon Mac, that changes. On those more modern machines and operating systems, booting from external drives is significantly more difficult and tricky to accomplish. I think it would be good to get into the habit of using TM more, as that is all you will need for a more modern system. If you are worried about the TM drives failing, use two with TM and let them alternate automatically for you. That way you don't need to be in the copying business at all, and TM will quite happily switch from one to the other every backup. If you leave the defaults on, then the newest backup will be no more than 1 hour old and the older will be no more than 2 hours old. I you feel you cannot last without a clone for an immediate reboot, go ahead and make one, but don't consider it a "backup" as much as an emergency boot drive. Your backup structure would be TM.

 

[peacockharris]

I stand corrected RE: Sierra. Guess it's more of a hidden feature.

I've actually always had 2 TM drives backing up alternately, but once had both become unreadable at the same time, presumably due to some blip with Time Machine. No idea why it happened, and thankfully I didn't need to go 'back in time' for anything. I just reformatted them and started from scratch. But ever since, I've had an extreme level of paranoia about my backups, and always kept a 'spare' of my own.

 

[MacInWin]

I stand corrected RE: Sierra. Guess it's more of a hidden feature.

I've actually always had 2 TM drives backing up alternately, but once had both become unreadable at the same time, presumably due to some blip with Time Machine. No idea why it happened, and thankfully I didn't need to go 'back in time' for anything. I just reformatted them and started from scratch. But ever since, I've had an extreme level of paranoia about my backups, and always kept a 'spare' of my own.

I get it. I had the same kind of thing when my internal drive failed and my backup drive failed on the exact same day and I lost thousands of irreplaceable pictures. Now I have multiple backups on multiple drives. So, that is OK. But as you move away from older versions of the OS and maybe even into Apple Silicon Macs, the philosophy of having a clone changes. It's a long and complex discussion, but in a nutshell, AS Macs actually still look at the internal storage area for a hidden boot Volume that must be there or the machine simply won't boot. Once it has that boot info, it can then look for an external drive, when asked, to finish booting. But because the Volume in an AS Mac is part of the "fabric" of storage in the silicon, and not a separate device or chip, if the internal "drive" has a hardware failure, the Mac is dead, dead, dead. So, the use case for a bootable clone is more restricted in an Mx system than in an Intel system where the drive is separated.

That issue not withstanding, you can boot from a TM drive into Recovery, then reformat and reinstall the OS and recover from the TM backup to restore your system, assuming that the hardware is functional.

If you are running a business on Apple Mx Macs and absolutely need to be running again as fast as possible, what you would need to do is to have a spare Mac on a shelf, unopened or at least reinitialized back to factory standards, to use with your clone backup. Even then there is a concept of "Owner" that can stymie boot attempts from external drives. See this thread for more information: For those planning to boot an Apple Silicon machine from a clone backup, read this:

Most of the time, what I have seen is that backups to a networked drive with TM use sparsebundle format, and that sparsebundles are at bit "fragile" in that because of the deep compression used to minimize network traffic and speed the process, the backup can be totally lost if as much as one bit is out of order. And that is why I keep my backup drives on a separate, powered hub from the other drives I have. I try to isolate my backup hardware when I can.

 

[peacockharris]

Unfortunately, moving beyond Mojave and to non-intel macs isn't an option for me (at least for now) as I still use the no longer supported Final Cut Pro 7, and have a bunch of unfinished projects in that format. It hasn't been officially supported since Sierra (there are third party hacks to make it work in High Sierra & Mojave, but no further, and even then, with some loss of functionality that's pretty irksome).

But when my late 2013 iMac died late last year, I had to buy an outdated 2018 mini to get up and running again (the one being repaired right now).

Thankfully I managed to score a 'broken' 2013 iMac on eBay not long after I bought the mini, which I managed to get up and running as a spare, but it's on borrowed time I think.

Hopefully once the logic board is replaced, my mini will last many more years, but when I no longer have the option of an Intel Mac I'm not sure what I'll do at that point. I've tried and failed to make the transition to FCPX, and apple made it so you can't move projects over from one to the other anyway. Not without a lot of work and third party apps, and even then it's imperfect.

They've put me in the position where, years down the line, I might have no choice but to build an Intel Hackintosh just to run software I paid good money for.

Rant over.

 

[MacInWin]

Yep, being trapped into obsolete software sucks, for sure. Soon, you will be like the US IRS, who is trying to recruit boomers to come out of retirement to support their old legacy software.