STORAGE AREA NETWORKS: REDI For The Next Generation - Industry Trend or Event

Computer Technology Review,  Oct, 1999  by Marty Sanders

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It is impossible to address the issue of enterprise storage without Storage Area Networks (SANs) dominating the discussion. In the past year, SANs have been promoted as a storage panacea, promising to cut costs, improve data availability, and speed up user access to data.

The rush to support SAN technology has seen several key vendors launch SAN "initiatives" designed to accelerate the availability of SAN-based storage solutions. Additionally, organizations such as the Storage Networking Industry Association (SNIA) have been formed to produce standards for multi-vendor interoperability of complex SAN hardware and software components, although, by most estimates, this dream is several years in the future at best. While this broad spectrum of the industry runs at full speed to deliver the first generation of SAN products, a quiet revolution is underway among corporate users in industries spanning pre-press to financial services who are in the process of enhancing existing SAN installations with a new generation of powerful software applications that expand the capabilities of SAN technology. The next evolution of SAN software, which in reality is SAN architecture, is delivering new killer data management applications that are fulfilling the promise of SAN technology while the re st of the industry is still struggling with first-generation programs to interconnect disparate storage hardware.

STORAGE AREA NETWORKS: WHAT'S ALL THE SHOUTING ABOUT?

The buzz surrounding Storage Area Networks can be attributed to three key benefits: improved data availability, higher performance storage resources, and lower administrative costs through centralization of storage resources. In fact, a study by International Data Corp. estimates that a single storage administrator can manage 7.5 times more data on a SAN than on a decentralized storage system.

The basic technology behind SANs is a high-performance network dedicated to connecting storage resources and moving data over a high-speed Fibre Channel connection rather than the Ethernet connection of a typical local area network. SAN hardware architectures, combined with the right software applications, are capable of creating shared storage configurations, as well as server clusters operating as fault-tolerant and high-performance clusters.

A main feature of SAN architecture is the de-coupling of storage from individual servers. According to the Gartner Group, 55 percent of the cost of a server is for storage. With SAN implementations, storage is purchased as a centralized resource, freeing individual servers from the expense of high-capacity storage. Instead, SANs enable storage assets to be shared among multiple servers. Since the data movement between the host server and the storage device is over the Fibre Channel SAN, this architecture also eliminates the bottleneck created by moving large volumes of data over conventional lower bandwidth local are network cabling.

UNLEASHING SAN BANDWIDTH: THE VIRTUAL ADVANTAGE

The challenge of implementing a SAN for disk storage vendors is twofold-creating a connection between the server and the SAN to tap into the bandwidth potential of the Fibre Channel technology, and then providing a method to pump data fast across that connection. The MAGNITUDE Centralized Storage System relies on a 200MB/sec host adapter board, creating an extremely high-speed connection to any attached servers.

Conventional RAID I/O technologies, however, are unable to deliver data fast enough to capitalize on this huge bandwidth. Instead, a better solution was required and is addressed only by the most technically advanced software to provide virtualization. Using virtual storage software technology and intelligent queue management techniques, users can supercharge data I/O to more than 90,000i/ops.

REDI Storage Manager, for example, from XIOtech, can create up to 256 virtual drives from a MAGNITUDE storage pool of up to 64 physical disk drives of varying sizes. By taking advantage of the combined I/O bandwidth of all available physical drives, the REDI Storage Manager accumulates the performance of many individual disk drives and shares the total performance with every attached server.

The installed physical drive can be of any size and speed. Drives can be installed or removed while the MAGNITUDE is still on-line. As new drives are added, the new capacity is automatically mapped to the virtual storage and immediately made available. When volumes are removed, that capacity is recycled and instantly available to be assigned to another server. Storage virtualization enables improved capacity planning and load balancing as all attached servers to the MAGNITUDE SAN share the storage.

Virtual storage technology is being touted as one of the key benefits of SAN technology. The Gartner Group predicts that SAN-based storage virtualization will reduce the TCO of storage by 25 percent by the year 2003. While that timetable appears to be off by a few years, the potential cost savings are significant. Implementing the advanced SAN architecture has already produced significant cost savings for hundreds of users with its virtual storage features.