Huge snapshots for small backups
Q Why are Time Machine’s hourly snapshots so huge when it’s only backing up my Documents folder, and those backups are far smaller?
by MIKE GALVIN
A Local snapshots made by Time Machine as part of backing up are different from its backups. That’s because snapshots include every file and folder on the volume, thus can’t and don’t exclude those items which you or macOS exclude from backups.
A snapshot consists of a complete copy of the file system for an APFS volume at an instant in time. That includes many files whichis made, when the data for any of those files changes, or a file is deleted, the old data is kept so that you can restore the whole volume or any file from it. Snapshots therefore grow and grow over time, as they collect all that changed data.
