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Installing MacOS software on external disk

Starting with MacOS Catalina does MacOS have to be installed to APFS formatted disks?


i ran into an interesting issue with trying to install MacOS on an external drive where the installer upon rebooting said that it could not recognize the startup disk.


that stopped being a problem once I reformatted the external drive from HFS to APFS.


i am trying to find explicit documentation where this requirement is mentioned but I am having problems doing so. Therefore I am looking for confirmation.


thanks.

Posted on Aug 8, 2020 12:52 PM

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Question marked as Top-ranking reply

Posted on Aug 8, 2020 1:15 PM

The Catalina installer will format the target drive using APFS, automatically. If the target drive is formatted HFS+, then the installer will convert the drive to APFS without existing data loss.


This information has been circulating since before Catalina's name became public. APFS, only, and 64-bit software, only. Catalina will do just fine with drives formatted HFS+, just not as a boot volume.


See Disk Utility User Guide.

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Question marked as Top-ranking reply

Aug 8, 2020 1:15 PM in response to mackiedoo

The Catalina installer will format the target drive using APFS, automatically. If the target drive is formatted HFS+, then the installer will convert the drive to APFS without existing data loss.


This information has been circulating since before Catalina's name became public. APFS, only, and 64-bit software, only. Catalina will do just fine with drives formatted HFS+, just not as a boot volume.


See Disk Utility User Guide.

Aug 8, 2020 1:37 PM in response to mackiedoo

See…

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Installing MacOS software on external disk

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