An evaluation of storage strategies

Sharing digital information is the way business is conducted today. As the need and desire to share information has grown, Internet has been adopted as the preferred vehicle for digital communication and information sharing. Hence, we find a surge in networked world and people.

Given the magnitude and rate of change, it is no surprise that the underlying technology infrastructures necessary to support global networking lag the demands being placed on them. Storage infrastructures have not been adequately given the attention it deserves. Whether it is deep in the back office or distributed across the globe, information must be stored and protected. And there are already clear signs that the storage infrastructure must change to support this need.

While storage needs are growing more than 100 per cent, staff and associated budgets are growing an order of magnitude less. Since storage growth is exploding and consequently that of data, scheduling planned downtime has become increasingly difficult. E-commerce has also placed higher demands on storage, which must now provide faster access as well as excellent reliability and more capacity. These and other factors have resulted in outages that directly affect operational service levels. In this context, it is relevant that a strong and sound storage strategy is adopted.

Most sites are sufficiently diverse to require a combination of strategies for effective storage management. The key to success rests in being able to define which storage strategy should be deployed where, to meet the processing needs of the enterprise and to effectively manage storage assets. Many sites are looking at distributed storage in two ways. One is an evaluation of whether to use traditional SCSI or fiber connections between computers and storage devices. The second is a locational strategy for storage.

Today''s enterprise-wide networks and mixed computing architectures include mainframes, servers and client workstations in central and remote locations. This diverse computing landscape has organizations looking for progressive, distributive storage strategies that keep pace with evolving business needs. Key concerns are in the areas of price-performance, reliability and uptime, storage resource management and investment protection.

Within the latter, storage devices can be dedicated to specific mainframes or servers, or they can be distributed along the network in the form of Network Attached Storage (NAS), or used as a collection of highly-optimized, centralized network storage in the form of SAN (storage-attached networks).

Says, Vivekanand, Business Development Manager, Hitachi Data Systems, "The new economy has changed the rules of the game. In today’s knowledge based business world, business agility is the distinguishing factor or rather the competitive advantage for organizations. In practice it means faster response to customers, reduced time to product and importantly reduced time to market. To achieve this, organizations need to build a solid intelligent information infrastructure".

Any organization that wants to achieve business agility needs to look at Storage as a strategic investment rather merely a peripheral. Experts are of the opinion that organizations need to view storage differently from IT investment. In IT investments, organizations are used to depreciating IT assets because assets become less valuable over time. An intelligent organization moves up the value chain and start using information as a competitive advantage.

Three approaches to distributed storage

Server-Attached

• Direct SCSI connection between the server and the storage device (speeds up to 160 MB/s)
• Data flows at high speed between the storage device and its owner-server
• Server and storage co-located within 75 feet proximity
• Objective is rapidly processing user data requests in a dedicated server environment
• Well suited to high-speed transaction databases

Network-Attached Storage (NAS)

• Storage is attached to network, not a dedicated server
• Topology can be Ethernet, Gb ethernet or FDDI backbone
• Data and message traffic runs at up to1000 Mbits per second, in a traffic contention environment
• Storage is inexpensive and standards are established
• Well suited to file sharing applications (NT and Unix), Microsoft Backoffice and software development

Storage-Attached Network (SAN)

• A centralized storage bank is attached to a storage network
• Data traffic does not compete for bandwidth with message traffic, and runs at 100 Mbytes per second (200MB loop)
• Increased reliability and multi-pathing with switches, with ability to cover geographical distances between storage banks
• Standards are still evolving and system management tools are lacking
• Well suited to disaster recovery and centralized resource management using physically separate sites

All said and done, enterprises need to assess their strategic requirements and suitable architecture. As Anil Valluri, Director, Systems Engineering, Sun Microsystems, points out, "Enterprises as well as the vendors implementing the solutions need to understand the needs of organizations such as what applications are running, the operating systems and for what process— file sharing or database. They need to understand the type transactions such as random transactions as in OLTP (OnLine Transaction Processing) or sequential transactions as in Datawarehousing. The enterprises need to look at some of the basic parameters such as scalability, performance and availability of solution and accordingly configure the strategies to be adopted while implementing".

Concurs Vivekanand, "One storage architecture will not meet all needs-it would vary as widely as applications. Also, the storage infrastructure must be open and interoperable, and easy to manage. Most importantly there should be no performance degradation when scaling."

The following is a note on which architecture suits what transaction. Often,

• Server attached architecture i.e DAS suits small networks and workgroups, and desktop process.
• NAS, the network attached storage, suits distributed server access and multi-protocol applications.
• SAN, the storage area network, suits all mission critical applications and reliable data access. This is recommended because SANs provide a host of benefits, including better resource utilization, improved performance, better security, centralised management and high availability.