This article can also be found in the Premium Editorial Download "Storage magazine: Distance: the new mantra for disaster recovery."
Download it now to read this article plus other related content.
The drive to better align data storage policies to business needs is spurring the development of new storage management tools. Two goals are improved efficiency of assets through better utilization and greater effectiveness of people through automation. These goals converge in a renewed effort underway by several vendors to reintroduce a technology that's been around for many years--hierarchical storage management (HSM).
This time-honored mainframe technology (see "
A solution in search of a problem? Several factors have combined to limit the adoption of HSM in open systems, notably:
- Dramatically falling prices for disk storage
- Distributed nature of open systems environments
- Fundamental characteristics of open system apps
This practice resulted in an increase in overall capacity, while utilization rates fell. Although this was wasteful, as long as the emphasis was on the cost of acquisition rather than the cost of management, it seemed reasonable. However, as administrative costs have begun to outstrip hardware costs, IT managers have renewed their interest in any option that can mitigate these costs.
The decentralized nature of open systems also discouraged the adoption of HSM. In the days of non-centralized, direct-attached storage (DAS), the opportunity to reallocate excess storage didn't exist. It wasn't worth the effort to recoup space from a particular system because there wasn't a way to effectively reassign it. With the onset of storage networks, reallocating storage has become more practical, so this objection no longer applies in many environments.
Nor does the issue of open systems' more interactive (vs. mainframe's) character. Open-systems applications tend to be highly interactive, whereas mainframes--to a large extent--perform huge quantities of batch processing. And the interactive nature of open-systems apps doesn't work well with HSM. If you directly applied the mainframe approach to open systems, when users attempted to access a document, for example, they'd be faced with an hourglass icon for several minutes. The potential increase in help desk calls alone is enough to discourage adoption of HSM. That problem is particularly apparent when tape is the target media for HSM data.
This was first published in May 2003