Bringing data backup into practical application: hierarchical storage management offers storage solutions for the dynamic enterprise - Storage Networking

Computer Technology Review, Nov, 2002 by Tom Yuhas

Hardware storage solutions have matured exponentially in the last several years to the point where once cutting-edge technologies, like storage area networks (SAN) and network-attached storage (NAS), are converging and tape library capacities have greatly increased. Thanks to new applications that allow greater access to data, rich media functionality, and unreserved file sharing, companies are more productive than ever, and storage technologies have successfully kept pace with the change. But with growth comes complexity, and improved storage capacities are meaningless without the ability to manage them effectively. While the average person might consider storage as simply backing up a server to disk, is this really using storage to its fullest capacity?

The easy answer is no, it's not. The more complete answer, however, involves a different question: How can businesses effectively utilize data, not just store and protect it, within an enterprise network? One solution that's opening new doors for network managers is hierarchical storage management (HSM), a concept that's been reinvented thanks to new network technologies and an increasing use of data in new applications.

Hierarchical Storage Management Defined

HSM is a software-enabled storage management method that is based on pre-determined policies that govern data migration. HSM systems automate file backup and archiving by managing data movement among tiered storage devices, such as SANs, disks, and tapes. Based on preset parameters of percent of usage, time, size, significance, and more, the driving idea behind HSM is to move rarely used files from networks or hard drives to more cost-effective archival media, such as tapes, in order to reduce the cost of storage management. HSM also saves money spent on replacing expensive media, since the process moves less-timely files to less-expensive media. This data movement is transparent to the user, who can quickly retrieve files whether they reside on a backup storage medium or an online network.

Thanks to the development and maturation of storage networking and crossbred systems, an affordable, flexible three-tier structure is replacing the previous HSM model, which was built on disk storage devices, optical jukeboxes and tapes. Today, the three-tier design is more efficient and provisional: SAN/NAS for online storage, followed by near-line disk storage and finally reliable, affordable tape storage for archiving and backing up files.

As opposed to other tiered storage system strategies, HSM promotes automated, hands-off data storage management, which is a crucial benefit for enterprise administrators who need to sustain data availability and limit, or eliminate, system downtime. According to an October 2000 Meta Group study, companies that are most dependent on automated systems--such as energy energy and telecommunications enterprises--accrue an average of nearly $3 million in losses for every hour of unexpected downtime, based on lost revenue and employee idling. Even industries that are less dependent on IT infrastructure--such as health care, media, and hospitality--lose between $330,000 and $636,000 of revenue per hour. The chance of unplanned downtime is not one a company can afford, arid an HSM solution reduces the risk.

Storage Networking Advances Usher in New HSM

Essentially, the goal of HSM is to align storage technology with application functionality, resulting in easier administration and better business. With new storage networking architectures, such as NAS, SAN, virtualization, InfiniBand, and iSCSI, creating an ideal web of networked users with seamless data sharing and storage capabilities, the HSM model emerges as an ideal choice in backing up all levels of data residing in multiple network locations. However, confusion exists about what HSM is and how to implement it. In fact, industry analysts consider general confusion in the marketplace one of the biggest obstacles to its adoption, explaining why the concept has not been more widely accepted outside the mainframe marketplace.

Although data backup is often considered the primary function of HSM, the need to effectively and efficiently use lower-cost storage media via HSM software is also a driving force behind the management approach. HSM has existed for about a decade and, until recently, its primary use was for specialized applications and system design. At the time, the approach of many administrators was simply to add more RAID as storage space was depleted. However, major corporations quickly learned that merely adding RAID was expensive and perpetuated the need for additional administration to determine what resided on it and how to properly control the expansion of the server system. As many administrators and companies now understand, adding RAID does not resolve capacity or management issues, and the search is on for a better approach, such as HSM.

Putting Theory to Work

An HSM system offers businesses time and cost savings that can be attributed to reduced management hours, maximum storage exploitation and cost-effective media usage. How-ever, in order to build an effective system, network managers must coordinate several aspects of an enterprise's overall business structure.