If you use Time Machine you’ll be aware that its backups don’t contain everything that they could. One obvious example is that, at least when backing up to APFS in Big Sur and later, you can’t back up your System volume any more. This article looks at what is and isn’t backed up by Time Machine in recent versions of macOS, in particular in backups made to APFS. If you want to read about Mojave and earlier, this article should help.
Time Machine has several mechanisms by which items are designated as not to be backed up.
Exclusion lists
The first of those exclusion mechanisms used to be its Standard Exclusions list, at /System/Library/CoreServices/backupd.bundle/Contents/Resources/StdExclusions.plist, but that disappeared without trace in Big Sur. Currently the only way to inspect that list is by locating the hidden file .exclusions.plist at the top level of any backup.
This lists several categories of exclusions, of which the first are apiExclusionPaths, which are added by individual third-party apps. The equivalent of what used to appear in StdExclusions.plist is now given under the standardExclusionPaths key, which contains:
- .DocumentRevisions-V100 – the version database on each volume, added in Big Sur,
- .Spotlight-V100 – Spotlight metadata,
- .Trashes – contents of Trash folders,
- .fseventsd – the File System Events database,
- /Library/Logs – traditional text log files,
- /Users/Guest – guest user files,
- /private/var (partial) – various transient files,
among other ephemeral items.
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