It's a long-standing problem: As data piles up on a server, completing a successful backup becomes harder. Backup apps become bogged down with millions of files to examine, and network and CPU limits can stall throughput when transferring a gigantic file. Even if a backup job is successful, the data in a large file may have changed in the hours it took to create the backup image. Vendors and users are now applying new ideas and technologies to ensure that no data set is too big to back up.

The rapid creation and accumulation of stored data has pushed traditional backup approaches to their breaking point. Large amounts of storage capacity and advances in processing power have led users to believe that a virtually unlimited amount of data can be stored and protected, but most backup managers will admit that it's just not so. While tape drives have become larger and faster, and new technologies like LAN-free and disk-based backup have reduced the load, the old approach of "scan everything every night and back up what has changed" is failing.