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HN · File systemsCurated

Apple File System replaces HFS+

Summary

Apple presents APFS as a modern file system with copy-on-write, snapshots, cloning, strong encryption and SSD optimisation. Apple announced APFS in 2016. APFS uses 64-bit inode numbers.

Ideas

  • Copy-on-write avoids directly overwriting existing metadata.
  • Snapshots preserve consistent file system states.
  • Cloning shares data blocks until something is changed.
  • Multi-key encryption protects different classes of data.

Insights

  • File system design combines consistency, performance and recoverability.
  • Copies become cheap as long as shared blocks remain unchanged.
  • Snapshots are local states and not an independent backup.

Facts

  • The file system later replaced HFS+.

Recommendations

  • Back up data externally before any file system migration.
  • Test snapshot restores and free space together.

References

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