What's needed
Enterprise storage networks present the ability for organizations to de-couple their application and information infrastructures and thereby generate both the flexibility and speed demanded of information technology today. Practically speaking, this means being able to move, add, and change application hosts and/or information storage systems without having to rebuild the infrastructure around the change. In order to achieve this goal, three design concepts should be considered. These are:
* Functional (Enterprise) storage. The information infrastructure must be functional enough to be capable of performing information-related tasks (such as data replication) independent of the application/host.
* Virtualization of storage. The information storage pool must appear (to the applications/hosts) as if it were contained in a single array making information able to be accessible from anywhere (in enterprise).
* Virtualization of applications (hosts). Applications software must be host agnostic, that is, it must be capable of being deployed on one processor today and on a different processor tomorrow. While full implementation of these design concepts together would create the most flexible infrastructure, it is often neither workable nor necessary. More practically, organizations use the applicable portions of these design concepts to meet a balance of their current and anticipated future needs.
SAN Or NAS
Given the availability of the multitude storage networking technologies, probably the first consideration should be whether to implement a storage area network or network attached storage. SANs provide the characteristics of a dedicated storage connection while, at the same time, allowing robust network topologies to be created to meet complex connectivity needs. Despite the 100MB bandwidth of a fibre channel connection, the primary benefits of a fibre channel network are the flexibility in distance and connectivity that it offers. Because of these advantages, organizations can realize the benefits of flexibility and speed in their information infrastructures. For these reasons, SANs are well suited to those applications where dedicated storage is required. These include: client/server applications, databases, and applications that require high performance storage.
NAS offers the ability to share the exact same file with multiple hosts in a heterogeneous environment at the same time. In addition, NAS leverages the very mature local area network technologies to provide the networking. These technologies are both cheaper and more mature than their fibre channel counterparts. On the other hand, local area network performance is not as predictable as channel based architectures. For these reasons, NAS is well suited for file serving (network directory) consolidation and file serving applications (eg. CAD, SW development, Web hosting, or Web mail).
While both technologies offer advantages and disadvantages that help decide which technology best meets the specific needs of a given environment, it is often the case that enterprise storage network implementations require both SAN and NAS. For example, a typical enterprise environment will have network shared directories and web serving (well suited for NAS); and at the same time, have client/server and database applications (well suited for SAN). Further, in many cases, the file server used for NAS can be connected on the SAN to its storage. Enterprise storage networks are a marriage of enterprise storage, storage area networks, and network attached storage. While there is much debate about the ultimate storage network technology winner being either SAN or NAS, it is more practical to consider where each technology can be best applied to achieve the information needs of the organization. It is often the case that the two represent complementary technologies. More importantly, it is important to understand the organizational forces that are driving the need to implement an enterprise storage network. The information infrastructure should then be designed leveraging the available storage, SAN, and NAS technologies to best meet the current and future needs of that organization.