I'm unable to boot a MacBook clone from a partition on an external drive. Though I'm able to select the clone as a startup disk in System Preferences and in recovery mode (cmd+R), at restart the MacBook just boots the internal drive. What gives? Am I not able to boot from a partition of a external drive? Do I have to dedicate an entire external drive to the bootable clone ?
I'm in the process of finally upgrading the OS of my mid-2012 MacBook Pro from Yosemite to Catalina, and need to make a bootable clone backup of my Yosemite machine.
I followed this process:
- repaired + verified the MacBook HD with First Aid in Disk Utility and ran an Apple Hardware Test. Everything a-ok.
- In Recovery Mode, I used Disk Utility to create a clone on a partition (OS-Extended (Journaled)) on a 5TB Seagate Backup+ external drive with a GUID partition map scheme. The rest of the Seagate drive is used for document backups. It is self-powered and connects via USB 3. The size of the MacBook drive is just under 500GB. The size of the partition is 550GB.
thanks for any help!