Add rate limiting for backup

**Feature request**
It would be great to have backup for validation.

**Use case**
Many users need this functionality for production deployments.

**Implementation idea**
Add a new config option `enable_backup` with default `false`.

The issue names no files, tests, or entry points. First clarify whether the request is backup validation or rate limiting, then identify the configuration and backup paths involved; done should include the requested behavior and an `enable_backup` option whose default is `false`.

Written by the indexing model from the issue text.