What does redundancy ensure in data storage?

Redundancy in data storage primarily ensures that there is proper storage availability even if devices are damaged or offline. This concept involves maintaining multiple copies of data across various devices or locations, which allows for continued access to the data under adverse conditions. When one device fails or becomes inaccessible, backup copies stored elsewhere can be utilized to prevent data loss and maintain availability. This is particularly important in scenarios where data integrity and access are critical, such as in business operations or cloud storage services.

The other options do not relate to the primary purpose of redundancy. Compressing data is about optimizing storage space and access speed, which does not inherently involve redundancy. Authentication concerns the verification of user identity and access rights, whereas redundancy focuses on data preservation and availability. Locking down devices from network access is a security measure rather than a mechanism to ensure data availability. Therefore, redundancy plays a crucial role in ensuring continuous access to data, even amidst device failures.