Which of the following are the application scenarios of elastic load balancing? (Multiple choice)

Each cloud server backup can only create one whole machine image, For cloud server backups that have already created the entire machine image, the entire machine image cannot be created anymore.

cloud hard disk backup support through()Record operations of backup service resources, So that users can query, audit and backtrack.

The disk capacity of the relational database is insufficient. In which way can it be solved?

Description of health check, Which ones are correct?