The key metric that should be used when updating the corporate disaster recovery plan to minimize data loss is the Recovery Point Objective (RPO). RPO defines the maximum acceptable amount of data loss measured in time before a disaster occurs. By aiming for a lower RPO, organizations can ensure that they would lose less data in the event of a disaster.

Graceful degradation refers to the design concept where a system continues to function in the presence of partial system failures, albeit in a reduced capacity. This implies that when some modules are unavailable, the entire application doesn't go down, but rather continues to operate with limited functionality, maintaining service continuity to some extent. Thus, the statement 'Some modules are unavailable, but the entire application has not been brought down' correctly describes graceful degradation.

In object-level deduplication, a hash is created from the content of the file. This unique hash, also known as an object ID, is used to identify and eliminate duplicate copies of the same data. The deduplication process relies on the hash values to determine whether identical content is already stored and thus can avoid storing redundant copies.

The key functions of data management include discovery and operations management. Discovery involves identifying and cataloging data sources, while operations management involves overseeing the creation, storage, maintenance, and utilization of data. Together, these functions ensure that data is accessible, reliable, and well-governed.

The Cloud Gateway Appliance provides a translation layer between standard storage interfaces and the cloud service provider. This means it enables applications to interact with the cloud service provider's storage services using familiar file and block-based storage interfaces, which are then translated into the cloud provider's API calls.