DLM Offers Graded Tiers
of Storage"> A common thread among DLM solutions is that they rely on graded tiers of storage and facilitate the movement of data from tier to tier. The logic behind using storage tiers is that as data gets older and is less frequently accessed, it should be stored on more inexpensive storage devices. For example, primary-storage-tier devices, such as Fibre Channel storage systems, offer the fastest performance but also have the highest cost based on price per megabyte of storageseveral times as much as simply archiving data on tapes. Moving stale data from the primary storage tier to a nearline storage device or a long-term archive, such as ATA- drive-based arrays, optical libraries or tape silos, can save a lot of money."[DLM has helped customers] focus on and justify creating policies for the storage, retention and, ultimately, the disposition of all different types of electronic documents and unstructured data," said Veritas Software Corp.s Brenda Zawatski, vice president of product and solutions marketing, in Mountain View, Calif. "In addition, customers are seeing economic benefits by being able to leverage their existing investments in data management while creating a DLM solution to comply with regulations." HSM systems tend to be one-dimensional in the sense that data is moved based on elapsed time since last use, according to Storage Technology Corp.s Mark Ward, vice president and general manager of Information Lifecycle Management Solutions, in Louisville, Colo. However, in todays business environment, information must be moved on a proactive basisfor example, to address quarter-end processing or retention for regulatory needs, Ward said. Although HSM has been around for several years, it has never been popular in open-systems environments (compared with mainframe environments, where they are common). "HSM solutions, particularly in open systems, have not gained traction in the marketplace as readily as you might expect," said Karen Dutch, vice president of product management for Fujitsu Software Technology Corp., in Sunnyvale, Calif. "HSM solutions have some inherent problems in a multivendor environment. Management of the solution with symbolic links or stub files can be extremely time-consuming and is easily corruptible. Because of these limitations, there are serious concerns about the scalability of HSM systems." Next Page: ATA: An Attractive Option
While the concept of storage tiers is an old idea thats commonly associated with HSM products, DLM solutions include features that will meet todays business needs.