At 1 meg, are you not counting storage of the file names and paths? The user has 700000 files. Each is probably >10 char of UTF8. In step 4, you also want to

At 1 meg, are you not counting storage of the file names and paths? The user has 700000 files. Each is probably >10 char of UTF8. In step 4, you also want to catch things like the user moving 50000 files to a new subdir, or renaming a top level subdir, while the sync app is not running.