volumeSupportsPersistentIDsKey semantics

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This post is from the WWDC26 File Systems Q&A.

What does volumeSupportsPersistentIDsKey represent and guarantee on macOS? Is it specifically about persistent filesystem object IDs such as fileIdentifierKey / inode / systemFileNumber, or can it refer to other kinds of persistent IDs?

For which common volume/filesystem cases would this property be false, and what should I fall back to as file identity in those cases?

Thanks!

Answered by Engineer in 891099022

As implemented on the underlying filesystem(s), it represents the persistence in the file system's inode numbers and more importantly, the ability to refer to the files system object by the inode numbers. Not all filesystems shipped with macOS export this ability (I believe it is only APFS and HFS)

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Engineer OP

Apple

10h

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As implemented on the underlying filesystem(s), it represents the persistence in the file system's inode numbers and more importantly, the ability to refer to the files system object by the inode numbers. Not all filesystems shipped with macOS export this ability (I believe it is only APFS and HFS)