STORAGE AREA NETWORKS: REDI For The Next Generation.

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.

THE NEW KILLER APPS: SANS READY FOR ACTION

Storage virtualization is just one application that the market is projecting as key software components required for successful SAN implementation. Here is an overview of the critical SAN software applications and how some advanced SAN software already meets the need of next generation SAN applications:

* CLUSTERING

Server clustering generally falls into two categories: availability clusters and performance clusters. Availability clusters are used to create a level of server fault tolerance. In this model, if one cluster of servers fails, another server immediately takes over its functions. Performance clusters rely on the combined processing power of the entire cluster to tackle computer-intensive tasks. In both clustering setups, the SAN serves as the high-speed backbone to enable all severs in the cluster to share a common storage pool.

XIOtech's REDI Zone, for example, provides complete clustering and SAN file sharing support. It enables multiple servers to share the same storage volumes. The MAGNITUDE centralized storage platform also supports third party clustering software such as Veritas First Watch, Novell High Availability Server, or Microsoft Cluster Server.

Another feature in XIOtech's REDI Volume Director is the ability to perform data zoning and LUN masking in FC-AL environments. These capabilities make it possible to ensure that the proper data is assigned to the proper server without fear of data corruption

* SERVER FAULT TOLERANCE

Building a fault-tolerant solution requires that any single point of failure be addressed and designed for bulletproof hardware redundancy. A software solution must eliminate the server connection--including Host Adapter Boards--as a potential failure point by allowing a dual connection configuration from a server to the SAN. The dual connection capability must support automatic failover if one of the server connections fails, maintaining continuous data and server availability. Dual server connections also support load balancing to improve performance.

Supporting mirrored servers in clustered configurations is another means of fault tolerance. In this case, the entire server is mirrored to another server in the cluster with immediate failover if the main server goes down.

* ZERO BACKUP WINDOW

With huge volumes of data at risk, performing backup operating within tight time windows is becoming a universal problem. Even more troublesome are operations that must be performed in 24/7 shops, in effect providing no backup window at all. Administrators, with the proper SAN architecture, can create unlimited copies of virtual drives at the speed of IGB/min. The copy of the virtual drive can then be backed up to any available backup device on the SAN, while the original source virtual drive stays on-line and available to users. This capability also makes it easy to create copies of data for Y2K testing and other non-production applications without the danger of corrupting the original data.

* REMOTE MONITORING & MANAGEMENT

Centralizing storage resources without the tools to manage those resources more effectively makes little sense and will not provide the dramatic cost savings that SANs must offer--a system must be designed to be configured and monitored from anywhere in the world. An administrator should be able to remotely monitor all performance characteristics and create, delete, and relocate virtual drives from any attached servers.

A SAN should provide IT Managers with full automation of storage management functions. An administrator can then schedule activities such as copy and backup operations and can create executable lists of management commands that implement customer specific applets.

* DATA VAULTING

Keeping duplicate backup copies of data in offsite storage is another method to ensure disater recovery. SAN software should enable an administrator to perform a copy operation of designated data to a group of physical disk drives. The physical drives can then be removed and stored in vaults of offsite. If a disater strikes or a critical backup fails, drives are then ready to be quickly installed in the SAN and operations can continue with minimal downtime.

* DISASTER TOLERANCE AND RECOVERY

The only way to guarantee 100 percent availability and complete disaster tolerance in the event of a catastrophe is resource duplication. The mirroring of geographically remote SAN systems ensures continuous operation. Automatic failover is supported with a backup of the SAN replacing the first with all data intact.

Storage Area Networks are revolutionizing distributed network storage. As SAN hardware designs become more prevalent, customers will increasingly look for innovative software applications to increase the return on their investment in SAN technology. The REDI software architecture is an example of a SAN software suite that has evolved into a second generation of applications that not only provide customer value, expanding the usefulness of the MAGNITUDE hardware, but also functions as an integrated set of applications to deliver customer benefits that are not available else-where. This generational approach to expanding the SAN software application base will enable users to further enhance their data management capabilities with each new application, building on the previous generation of functionality to provide new innovative benefits. As new killer apps appear, data stored on servers explode, and the ever-more popular 24/7 environment exists when a SAN full-function solution of hardware and software designe d for compatibility and minimal downtime is employed, IT managers will painlessly move into REDI mode.

Marty Sanders is the product manager of advanced solutions at XIOtech Corp. (Eden Prairie, MN).