Which AWS Storage Gateway operation is needed if they encounter a failure?

When dealing with AWS Storage Gateway and encountering a failure, the operation that directly addresses the immediate issue is to mount the cache disks to an ephemeral drive. This step is relevant because cache disks play a crucial role in the operation of the Storage Gateway. They temporarily store frequently accessed data, reducing latency and improving performance by enabling faster access to cached information. If there are issues related to the cache or its operation, mounting the cache disks appropriately can help restore functionality and troubleshoot any problems.

While other options might seem viable, they do not directly relate to resolving a failure of the Storage Gateway in the same straightforward manner. Initiating a backup does not specifically address the failure itself; it is more of a proactive measure to safeguard data. Rebooting the gateway might help if the issue is systemic, but it doesn't guarantee a resolution without understanding the specifics of the failure. Redesigning the network architecture is a more drastic and time-consuming option that would typically be unnecessary unless there are ongoing structural issues that are not just localized to the failure. Thus, mounting the cache disks directly aligns with the need to address a failure in the immediate context of AWS Storage Gateway operations.