Howto: Clone High Sierra to another disk using macOS

[EvdK]

Recently i upgraded to High Sierra on SSD on my mac pro 5.1. During this proces the filesystem got upgraded to APFS but after that i wanted to upgraded the bootdisk.
Of course you could use commercial software but it is doable with just macOS and a third disk or usb stick to store an image, as i did below.

In this case my original disk is disk0, the new disk is disk1 and the backup 'disk' folder is <backup>:

1. Boot mc with original disk/SSD and the new disk/SSD
2. In macOS erase the new disk with Disk utility and create a APFS volume. Dont worry about the name.
3. Start your mac in recovery mode and open a terminal window. I opened 4 terminal windows to keep track of information
4. Unmount de the original disk and the new disk. Type 'mount' to get an overview.
   1. Statement 'unmount /dev/disk0s2' and 'unmount /dev/disk1s2'
5. Create an image with hdiutil
   1. Statement: 'hdiutil create /Volume/<backup>/Image.dmg -srcdevice /dev/disk0s2'.
   2. For 100GB this will take approx 15 minutes on my system.
6. Start asr to scan the image
   1. Statement: 'asr imagescan /Volume/<backup>/Image.dmg'.
   2. This is required before the image can be restored. This proces requires 15 minutes to run on my system.
7. Use asr to restore the image
   1. Statement: 'asr restore -s /Volume/<backup>/Image.dmg -t /dev/disk1s2 --erase'
   2. This proces also requires 15 minutes to run on my system
8. That should be it. Remove the old disk and boot with the new disk.

I also used 'diskutil list' besides 'mount' to get an overview of disks and volumes. If you are in recovery mode, you will also see a lot of temporary volums but you can ignore those.

Good luck!