Cloud storage, Harr said, should be scalable from gigabytes to exabytes while using a single global namespace; load balancing will allow resources to be shifted to different geographic locations based on demand. Cloud storage should also be easy to connect to through Web services APIs or standard storage protocols; feature a fully redundant infrastructure; and be 80% to 90% less expensive than building one's own storage, he said.

Nirvanix offers cloud storage over the Web through its Storage Delivery Network, which is similar to Amazon's S3 storage service. Nirvanix on Monday announced general availability for a storage software offering called CloudNAS, an add-on to the Storage Delivery Network that lets users connect systems to Internet-based storage nodes via NFS, CIFS or FTP.

The most common use cases include storing large digital libraries, integration of online storage into devices or applications, and backup and archival, Harr said. "We're seeing a lot of excitement in the archival and backup space," he said.

executives also spoke about the cloud Monday, saying cloud storage should provide both an infinitely scalable pool of storage and a simple way for users to access it. If built effectively, the incremental cost of managing newly added resources should be close to zero, said Stephen Edel, IBM's storage portfolio management program director.

Rather than offer its own cloud storage service, IBM is focusing on delivering the hardware and guidance necessary for service providers to build externally available clouds, as well as helping enterprise IT shops build internal clouds behind their firewalls.