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June 16-30, 2001 NETWORKING |
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Master
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CHANNELS Politics
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STORAGE AREA NETWORKS (SANs) Getting Bigger and Better If your firm is heading towards, or has already crossed, the terabyte mark in storage, it's a prime candidate for a SAN migration. And if you're expecting significant growth in storage requirements, it's high time you developed your own strategy. By Monalisa Sen
Going by these figures, one can safely make out that to conduct E-commerce huge storage spaces are required. In this arena two new emerging storage architectures that dominate suppliers' new offerings are the Storage Area Network (SAN) and Network Attached Storage (NAS). These architectures share several objectives, but achieve them in different ways. Both SAN and NAS provide scalable storage capacity and performance, a clean separation between server and storage purchasing decisions, the ability to serve multiple users in multiple operating environments and support for high availability. The two approaches are distinguished primarily by the location of the network when interconnecting users and applications, a file system and a collection of disk drives. NAS products connect to an organisation's regular data network and provide a file system interface to applications or servers. NAS devices thus look very similar to standard file-servers, although they are typically designed storage appliances rather than general-purpose computers. SANs, in contrast, use a dedicated high-speed network-often fibre channel-to connect storage devices to servers, with the interface being a disk block protocol. Until recently, storage devices were usually attached to individual computers or to servers. But one current trend is to centralise large-scale data storage and retrieval functions into their own separate network. Today an increasing number of companies are moving towards SAN. By the year 2003, the investment in storage is expected to surpass those in servers, meaning thereby that the storage industry would be one of the fastest growing ones, points out a survey. With the explosive growth of E-business, IT managers are working intensely to keep pace with managing the significant growth of data (multiple terabytes per year.) They are installing high-performance storage systems to meet the demands for smaller backup windows and greater application availability. However, these systems are sometimes complex and expensive to manage. In addition, they are often single platform, restricting access to data across the network. To improve data access and reduce costs, IT managers are now seeking innovative ways to simplify storage management and SAN is a promising solution. What is SAN? A SAN is simply a method of providing access to enterprise storage, consisting of many servers, through a fibre channel switch. The storage thus connected through the switch becomes a part of the network dedicated to accessing the servers. SANs are extremely beneficial to corporations with heterogeneous servers. SANs ensure that the storage can scale independent of the servers that are connected to it. Direct attach storage can only scale along with the server that it is attached to, whereas SANs allow flexibility to use and scale the increased information across multiple servers. SANs also provide tremendous flexibility in deploying new applications, as the backup and restore mechanisms inherent in the storage infrastructure can cascade across existing and new applications. Finally, given the fact that storage requirements are likely to double every 12 months, manageability of the information explosion is best done through scaleable implementations of SAN. SAN is based on a systematic approach to data storage management pioneered by IBM in the environment almost 30 years ago. SANs are now rapidly being integrated into distributed Net environments using fibre channel technology. It is a dedicated network that connects servers and storage devices. A SAN is an architecture for building special, dedicated network that allow rapid and reliable access to storage devices by multiple servers. Like a LAN (local area network) or WAN (wide area network), a SAN is built using hardware, protocols and topologies. SAN hardware includes devices such as a hub or a switch that carry data around the network. A SAN protocol is the shared language that each hardware component uses to pass data packets along the network. The general requirements for an effective SAN are: Centralised management of data to provide universal data access, regardless of the operating systems used by different application servers; integrated data protection and fault tolerance; built-in security; and a high degree of scalability to meet rapidly shifting corporate needs. Other requirements are routing of storage and back-up data traffic over a separate, dedicated network to avoid further traffic on the enterprise network, increasing intelligent storage systems that provide facilities such as automated data snapshot to solve the problem of backup for huge data. Generally SAN architecture have two major components: The interfaces between host systems and storage devices, including SCSI, IBM SSA or FC; and the interconnects which consists of extenders, multiplexers, hubs and routers and the switching fabric, along with the dedicated fibre optic or copper cables that carry data within the SANs. The physical architecture of a SAN usually comprises a storage manager, storage devices such as disk arrays or tape arrays and bridges and multiplexers that provide the backbone for all linked devices. As the SAN architecture is relatively new, it has some limitations-the biggest being lack of interoperability between different SAN vendors' fibre networks. Although current efforts to create standards, to test for interoperability and to create development projects among vendors, may overcome some of these difficulties in the future, mixing FC switches from multiple vendors is still in an early stage of development. One of the important characteristics of a SAN architecture is that it is zoned-that is, divided into subnetworks that accommodate different degrees of connectivity among specific devices and hosts on a given network. Benefits of the Network Storage area networks remove data traffic, like backup processes, from the production network giving IT managers a strategic way to improve system performance and application availability and improve data access. Using fibre channel connections, SANs provide the high-speed network communications and distance needed by remote workstations and servers to easily access shared data storage pools. IT managers can more easily centralise management of their storage systems and consolidate backups, increasing overall system efficiency. The increased distances provided by fibre channel technology make it easier to deploy remote disaster recovery sites. By implementing a SAN to support business one can realise improved administration, consolidation and centralised management/control, resulting in cost savings. Also, any-to-any connectivity, advanced load balancing systems and storage management infrastructures can significantly improve resource utilisation. Implementation of SAN The early implementations of SANs will be for specific applications, including the following:
Different types of servers, including Unix, OS/390 and Windows NT can share a SAN. These servers can be connected to the same set of storage systems, but whether they can actually share storage devices or even share data depends on the operating systems and on the storage devices. Anticipating the growth of the SAN market, enterprise storage vendors are evolving their products to be connected to servers via SANs. Enterprise storage providers are the suppliers of large-scale products and traditionally these products are attached to multiple servers. The companies which are engaged in this storage activities are EMC, IBM, Storage Technology, Sun Microsystems, Compaq, HP, Amdahl (a subsidiary of Fugitsu) and Hitachi. Outsourcing Storage With such an impressive resume, the SAN architecture should be a hands-down winner in the storage context. Any company planning to increase storage significantly should consider a SAN. Interestingly, this is not what an Enterprise Storage Survey conducted by Info- World indicates. In fact, only 14 per cent of the IT leaders InfoWorld surveyed said they had a SAN installed, and only 10 per cent planned new implementations. The participants indicated that the main reasons for not implementing a SAN were lack of internal knowledge, high cost, and the perception that it is a solution for larger companies. If you recognise yourself in this picture, outsourcing your needs to a service provider with a SAN could be the right solution. Without the need to master new technologies or to make huge, up-front investments, you can achieve the benefits of having a SAN without actually owning one. Every company faces challenging choices, and choosing the right storage architecture tops the list. Market Overview In 1999, only $2.2 billion of the $30 billion spent worldwide on disk storage was spent on SAN or NAS devices, according to IDC, but this will shift dramatically in the next few years. IDC predicts that by 2003 combined NAS and SAN acquisitions will exceed one-third of the estimated $46 billion disk storage market. While SAN and NAS products represented about 7 per cent of the overall storage marketplace in 1999, IDC expects these products to account for 38 per cent of the market in 2003. It also expects distribution channels to change for some storage products. Indirect channel players will continue to supply enterprise customers, particularly over the Internet, to grow dramatically. According to the InfoWorld survey, around 96 per cent of participants will increase their storage capacity in the next 12 months. If you are planning to add more than half of your firm's current capacity to your storage pool, you should explore possible alternatives that offer flexibility and are less costly to manage than current implementations. How is SAN Different from NAS? While sometimes incorrectly depicted as competing technologies, NAS and SAN are different answers to different storage needs, and are not only complementary, but in some ways starting to converge. If you've ever called up a file from a shared drive on Windows-the "G: \drive," for example-then you've used a simple form of NAS. The same concept can be applied to the Internet, where dotcoms send files (Web pages) to many users simultaneously. NAS can also be used for a host of applications: software development, streaming video, and engineering design, among them. But that's not saying that NAS is the answer to "all things storage"-far from it. NAS is useful for specific functions, but inappropriate for others. For example, data warehousing, CRM or ERP, all of which represent major portions of the storage market, are not an appropriate role for NAS. The key thing to keep in mind is that file serving is fairly simple: NAS "serves up" files over the network for the purpose of sharing. That's it. Also, databases often have a great deal of indexing, and may be performance-limited in network file serving environments. Yes, it's possible to build a database on a file server and connect an application server over a network; but it is usually more efficient and effective to use a SAN. In addition, the value of NAS comes from the sharing of individual files. Databases can't be shared. |
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Buying
and selling goods over the Net require huge storage capacity and Web sites
such as Yahoo or Rediff consume massive space to facilitate E-commerce.
According to a Confederation of Indian Industry (CII) release, E-commerce
activity in India is expected to increase from Rs 450 crore in the
financial year 2000-01 to Rs 25,200 crore in 2005-06. It also says that
the B-to-B E-commerce turnover will increase from Rs 400 crore in the
financial year 2000-01 to Rs 23,280 crore in financial year 2005-06. The
total worth of B-to-C E-commerce activities in India is expected to
increase from Rs 50 crore in the financial year 2000-01 to Rs 1,882 crore
in 2005-06.
