Dataless macOS File Versioning
When an app that supports versioning saves a file, the current version is added as a dataless file to a folder in AllUIDs, with its UUID as its name, its data are added to the ChunkStoreDatabase, and its details are added to the database in db-V1. Chunk sizes typically range up to just over 20 MB. The service responsible for versioning is
revisiond, and the subsystems you’ll encounter in the log are com.apple.foundation.filecoordination and com.apple.chunkinglibrary.Retrieving a version thus consists of looking it up in the db.sqlite database, and reconstituting that version as a file, using the dataless file with its attributes and metadata in the file UUID, and its data restored from the ChunkStore.
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The most common cause of problems with the version database is excessive size. Although its size isn’t readily discoverable, it can be a major contributor to that attributed to System Data in Storage settings and third-party utilities, and in some cases can exceed 100 GB.
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My free utility Revisionist has a version crawler that will list all files in a volume or folder with the number of versions they currently have stored in that volume’s .DocumentRevisions-V100 folder.
In recent discussions here about the version system built into macOS, two potential problems were raised: first that a file’s versions don’t go with it wherever the file goes, and second that versions wouldn’t preserve datestamps. This article demonstrates how you can easily work around the first, and how the second isn’t correct.
Previously:
- Tahoe Free Space Problems
- What to Do When macOS Won’t Let You Unmount a Volume
- iCloud Drive Switches to Dataless Files
- iCloud Drive Now Supports File Versions
- Mac Backups and the Versions Database
- Document Versions and iCloud
