backup disk formatting

[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

[dnanian]

That was a long time ago...

[Dan Lester]

True, but that's the machine we're talking about here. MBP late 2011. But I agree that Apple doesn't seem to do such updates for contemporary machines.