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My understanding was that recent versions of Mac OS have an upgrade process that works a bit like this anyway — i.e., behind the scenes it's doing a fresh insta

by gmac 9y ago

My understanding was that recent versions of Mac OS have an upgrade process that works a bit like this anyway — i.e., behind the scenes it's doing a fresh install, then copying your files back across. But I could be wrong.

falsedan 9y ago
> behind the scenes it's doing a fresh install, then copying your files back across Are you thinking of the reformatting to APFS? That's kind of done like this. Aside from this, the OS upgrade is the same as it always is: install the new system-level packages over the existing files & reboot.
- pohl 9y ago
  The migration from HFS to APFS does not move your files at all. It leaves the files exactly where they are on the disk. Instead of moving the files, it writes new the new APFS metadata onto unused areas of your disk. When it's done with that, it changes the superblock header to point to the new APFS metadata. Then it marks the old HFS metadata as blank space. Your files are not moved or copied. By doing it this way, they make the dangerous part of the process as small as possible. They actually did a dry-run to collect success/failure metrics before APFS was released to iOS devices: https://www.macobserver.com/analysis/apple-dry-run-apfs-prior-ios-10-3/ https://www.macobserver.com/analysis/apple-dry-run-apfs-prio...
  - falsedan 9y ago
    > Your files are not moved or copied. :extremely pedantic voice: ITYM your data is not moved. Your inodes are. :normal voice: thank you for taking the time to explain clearly this in more detail.