11/5000 How do I check if my backup is complete?

The source data is 56.58gb but the backup data is only 56.08. Is it because the compression is less than 500mb or is it the way it is? Is this normal?

Hi @xiaobaixuejava welcome to the forum.

If something did not work, you would get either a warning or an error displayed.
Since your screenshot shows 0 errors and 0 warnings, everything worked as is should.

Yes, it is normal. It can happen either due to compression or due to deduplication.
If you have the same (or mostly the same) file in multiple places, Duplicati only stores the unique parts.

The “Test” (“Verify files”) operation is mostly consistency checks that backup is intact.

It won’t detect a configuration accident (especially likely with complex configurations).

It might not detect an intact partial backup, e.g. if it was interrupted and then tidied up.

The Restore menu will show partial backups, and you should also browse the file tree,
especially if you use Source Filters or Excludes, which are easy to set up incorrectly…

If you’re sure your configuration is good, just watch for warnings and errors in job logs.
You ask about backup success, but didn’t post results. Are backup logs clean as well?

EDIT:

If a backup doesn’t complete, you should also get a red GUI popup and a red tray icon.
Warnings are not fatal, and the color is yellow.