backup disk formatting

[Dan Lester]

Just an FYI, not sure if it's been talked about before. I was trying to create a bootable backup for an old machine, for which the internal disk was formatted MacOS Extended (Journaled). The backup was accidentally done on an SSD that had been formatted with the modern APFS. When the backup was done, I did option-restart to get the Mac Boot Manager, and the backup disk DIDN'T APPEAR! When I did it again after reverting the backup disk to MacOS Extended (Journaled), everything worked dandy. Make sure your backup disk is formatted the same way as the disk you're backing up! Now, of course, older Macs can't read APFS, but you'd think that when SuperDuper is making a backup to a disk that isn't formatted in a compatible way, it would complain.

[dnanian]

If the OS supports APFS, we're happy to copy to APFS. Anything on 10.13 or later should be able to boot from APFS as well...unless that Mac has never had its firmware updated to add the support.

[Dan Lester]

Thanks. Not a big deal, but if the OS DOESN'T support APFS, it strikes me as a little funny that SuperDuper blasts ahead with trying to copy to a non-APFS disk. That is, you only find out half an hour later, when the copy you tried to make doesn't boot because, I guess, it isn't really there.

[dnanian]

If the OS doesn't support APFS, we would copy to a non-APFS disk...? And if the OS doesn't support APFS (eg 10.12) we won't.

If the firmware hasn't been updated for boot-time APFS support, we don't know - that capability isn't exposed. But installing the OS (rather then restoring) will ensure that the firmware is updated...these things are distributed with installers.

[Dan Lester]

Sorry, not being clear here. If you connect an APFS disk to an OS that does not know how to communicate with APFS, SuperDuper will STILL try to copy, and takes time grinding away seeming to do it. But what you end up with, after a long wait, is a disk that won't boot, and probably doesn't even have a copy on it. My point is that SuperDuper doesn't seem to recognize that it's trying to copy to a disk that the OS formally can't communicate with, and you don't find out until the disk doesn't work. Are you saying that SuperDuper has no way of polling the disk to see if it is really writable?

[dnanian]

No, Dan, it won't. If the system does not know how to communicate with APFS, the drive won't even mount.

[Dan Lester]

That makes sense but, as I recall, when I plugged that APFS SSD in to my High Sierra 2011 Mac, an icon DID appear on the screen. That's why I assumed I could back up to it. And when I commanded SuperDuper to back up to it, it ground and ground for twenty minutes and pretended to be backing up. It was only when I tried to boot from that backup twenty minutes later that the SSD didn't show in the Boot Manager. That is, the Boot manager knew that it wasn't a compliant disk, but SuperDuper didn't seem to be aware that it wasn't.

[dnanian]

Dan, it made the copy as it should. It didn't "pretend" to back up. (Feel free to send me the log to verify.)

If the boot manager doesn't see it, it may have had the wrong partitioning scheme, or High Sierra had never been *installed* to the system (it had been restored, or copied from elsewhere) and thus the BIOS doesn't have APFS capability, even if the *system* does.

[Dan Lester]

OK, that makes sense. Now, because I couldn't do the backup with APFS, I was assuming that High Sierra couldn't manage APFS. It can! I reformatted the backup disk to APFS with the High Sierra machine I'm backing up, did another SuperDuper backup to it and ... Boot Manager couldn't see that backup again. Same problem.

So to the extent a backup is really being made, for some reason the Boot Manager can't see it. The backup disk icon is sitting the desktop, as normal, and, if I can click on it, it has inside what sure looks like a backup. So the issue is precisely with the Boot Manager.

As I said, if I format the disk as MacOS Extended, and do the backup, the Boot Manager can see the disk just fine.

I am sending you the SuperDuper log for that backup.

[dnanian]

Install the OS on this system, Dan. (Sorry, didn't connect the log - which I got before this - to this forum thread.)

[Dan Lester]

OK, let me wrap things up here. Dave and I did some discussion offline, but he finally suggested just dumping my High Sierra and reloading it. That took some effort as the Apple instructions for recovery were poor, and loads of people have had problems with the "The recovery server could not be contacted" error and the 2000F error in the reinstall package which were a big waste of time. But I finally just went to the App Store, downloaded the OS and over-installed it that way. Bottom line is that now everything works GREAT. I can now back up to an APFS drive, and boot from it, which for some bizarre reason I was unable to do before. Problem solved. So my OS just got corrupted in some subtle way. Thanks to Dave for his sage advice.

[dnanian]

The OS wasn't corrupt - the BIOS/EFI wasn't updated... and that only happens when the OS is installed.

[Dan Lester]

Thanks. That's because the Boot Manager is in BIOS/EFI? The EFI partition loads the boot device drivers. I guess that's not part of the OS because you need it to start up the OS. Maybe all I needed to do was an EFI Firmware update? I presume when you download the OS, it does that automatically.

[dnanian]

Yes, everything before boot is in the EFI/BIOS. Firmware updates to that are in the OS install packages and aren't available separately.

[Dan Lester]

Well, but there is this ...

https://support.apple.com/kb/dl1499?locale=en_US