Some typical Cloud Storage use cases

Clustered application file sharing
Many applications must run in a clustered configuration that provides for load balancing, fault tolerance, and horizontal scaling, yet need common/shared access to a file repository. An example of this use case is a mobile app service used by hundreds of thousands of mobile devices that connects to a balanced pool of application servers that all serve a common set of image or data files.

Log data storage & retention
Application log data and/or syslog data can accumulate quickly on client machines whether they’re virtual or physical, so most administrators must implement a policy to manage that data. Many organizations also require log data management and retention policies to ensure security audit compliance, provide support for general informational analysis, and retain information for debugging. An example of this use case is a small eCommerce merchant that must transfer and retain syslog data pertaining to its credit card system processing.

File backup & retention
Application or database servers that use local attached storage will always need a location for targeting local file system backups. Cloud Storage is intended to be used as the target location for backup services.

High-volume file output
Applications designed for high efficiency and simple file-level unstructured data output can mount and use Cloud Storage as the repository for accumulating those output files and then making them available in bulk for re-retrieval and analysis. An example of this use case would be a web service that writes an individual log-event file for every call to the web service. This setup allows for efficient file output and makes the aggregate data subsequently available for analysis or for loading and analysis using map/reduce functionality.