According to the documentation the metadata-updater will do the following:
metadata-updater - Updates artifact metadata files depending on the content of the repository. I have been testing this by deploying several artifacts to the repository and getting a specific timestamp and build number in the maven-metatadata.xml file. Next, I delete the latest (snapshot) build from the repo, including checksums. I run the repository scanner and the database-updater and this file is never fixed based on the actual contents of the file system. Archive updates it internal metadata, but not maven's metadata and thus maven fails to download the artifact.
