I've received a new Mac that has come preconfigured with lots of junk.
Naturally, my first order of business is to wipe the disk and clean install macOS. But first, I want to create a bit-perfect, bootable clone of the disk (which is formatted APFS Encrypted) and keep it on a flash drive, in the unlikely event that I ever need to boot into the original environment.
I tried to create this clone by booting the machine into Recovery mode, attaching a flash drive of the exact same capacity as the disk and running
dd if=/dev/rdisk0 of=/dev/rdiskX bs=64k. I expected this to create an exact clone, especially reading at a raw level via
/dev/rdisk. However, the resulting drive is not only unbootable, but none of the APFS structure is preserved - I'm left with an
FDisk_partition_scheme partition type and a
Nothing in this answer proved useful in making this bootable.
More than "how can I do this," I'm wondering "why can't I do this."
dd perform the low-level, bit-by-bit replication that I'm looking for? Or, is it doing what I'm telling it to, but there's another factor at play that I'm not aware of?