Home > Articles > Networking > Storage

Types of SAN Technology

  • Print
  • + Share This
A storage area network (SAN) is an alternate network built out of storage interfaces. But the essence of SANs lies in the way in which enterprise storage is externalized and consolidated. John Vacca takes a closer look at SAN technology here.
This article is excerpted from The Essential Guide to Storage Area Networks (Prentice Hall PTR, 2002), by John Vacca.
Like this article? We recommend

Storage area networking (SAN) technology solutions are not new. Neither is the notion of multihost attached shared storage. All mainframe data centers are configured this way, and currently 25% to 35% of all network traffic passes over a SAN. What is new is that these tried-and-true technology architectures are being adopted in the distributed network, primarily through a storage topology called Fibre Channel. In other words, SAN is defined as an alternate network built out of storage interfaces. But the essence of what SANs really represent is the leading methodology by which enterprise storage is "externalized and consolidated."

The externalization of storage is one of the most important technology architectures to be adopted in distributed networking in the last 10-plus years. According to numerous studies of mission-critical applications conducted by Strategic Research Corp., server-bound storage is the greatest inhibitor to continuous access to data and is an impediment in achieving continuous operations.

Application availability is now the top priority in the distributed network. Server failover via clustering is broadly being deployed as one leg of a high-availability architecture. The other components include high performance, continuous access, data protection, and disaster tolerance. The access dimension is the number-one contributor to continuous operations. This is where external storage, especially centralized, consolidated shared storage attached via a high-performance fault-tolerant SAN, meets its destiny.


Storage area networking technology holds great promise, but the lack of workable automation software currently stands in the way of deployment. Imagine that all your storage devices were attached to a switch and could communicate with each other. And imagine that all storage administration and management was totally automated. With no need to guide storage and retrieval traffic, manage backups, or worry about the performance strain on your network; you could become the Maytag repairman of storage management (see Figure 1)1.

Figure 1 How the SAN structure works.

This isn't an impossible dream—it's all part of the promise of storage area networks (SAN). As defined, a SAN is a collection of networked storage devices, such as server hard drives, tape libraries, RAID, and CD jukeboxes that are able to communicate with each other automatically.

The automated management software required to make SANs a reality isn't yet available. However, the underpinnings of SANs are maturing (see the sidebar "Update: Fujitsu Sets Up U.S.–Based Storage Software Unit"), providing the technology for some useful, cost-effective applications that you can start using today.

Update: Fujitsu Sets Up U.S.–Based Storage Software Unit

Fujitsu Ltd. recently launched a new U.S.–based company that will develop and market open storage software products with the aim of competing against the likes of heavyweight vendors such as IBM and EMC Corp. The new Fujitsu Software Technology Corp. unit, which is being referred to more informally as Fujitsu Softek, is based in Sunnyvale, California, and will operate as a part of Fujitsu's Amdahl Corp. subsidiary. Fujitsu Softek combines products from the former Amdahl Software division with new storage management software that's now in the works.

Fujitsu indicated that the new company is being organized along five lines of business, including storage-management software, storage infrastructure, storage resource management, quality-of-service monitoring, and consulting. The upcoming storage-management software, a version of a storage networking package developed by DataCore Software Corp. in Fort Lauderdale, Florida, is due for release in 2002. Other new products, including one for monitoring quality of service, are available now as additions to existing Amdahl Software tools for migrating data between storage devices and other uses.

Nevertheless, software for managing storage area networks is still in its infancy. But it's quickly becoming a necessity for users who have hundreds of terabytes of data stored on networks made up of devices from multiple storage vendors.

Amdahl was looking for a way to reallocate some of its resources after disclosing a plan to exit the mainframe business in 2000. The new unit's software will work across multiple operating systems and support storage devices from different vendors.

  • + Share This
  • 🔖 Save To Your Account