A company uses an AWS Storage Gateway in file gateway mode in front of an S3 bucket shared by multiple systems. A third party uploads objects directly to the S3 bucket overnight, but in the morning the Storage Gateway cache does not reflect those new objects (the objects are present in S3 when checked directly). Which solution ensures the Storage Gateway has all updated third-party files available by morning?

The correct solution is to schedule a nightly Amazon EventBridge rule to invoke an AWS Lambda function that calls the Storage Gateway RefreshCache operation. When objects are uploaded directly to an S3 bucket that a File Gateway uses, the gateway's cache does not automatically update to reflect these changes. The RefreshCache operation forces the gateway to synchronize its cache with the S3 bucket, making the new objects visible. Scheduling this nightly ensures the files are available by morning. Requiring the third party to use AWS Transfer for SFTP would not resolve the cache synchronization issue, as files would still be uploaded directly to S3. Switching to volume gateway mode is inappropriate; file gateway mode is designed for file-based access to S3. S3 Same-Region Replication is for replicating S3 objects between buckets, not for updating a Storage Gateway's cache.