Chapter 20 addresses the usage of SAN and NAS as an integrated solution. Discussions will cover current data-center realities and experiences but also look to the future uses of integrated SAN and NAS technologies. Because many of the challenges to integration are hidden in managing multiple I/O workloads, just the introduction of this subject can be a complex exercise. This chapter was developed with a broad scope in order to provide a meaningful orientation for those uninitiated to storage strategies as well as prove valuable to those experienced with enterprise storage and I/O workloads.
Integrating storage networking models is, in many ways, like developing a client/ server-networking environment; it maintains some fundamental differences given the extreme architectures of SAN and NAS. The fundamental differences are block access in SAN operations versus file access in NASblock I/O being an extension of the server OS, and file I/O as a functional extension to networking technologies. Beyond these visible differences, the challenges of microkernel compatibility, communications standards, and caching coherency issues will require server and storage vendors to cooperate with synchronization, technology integration, and yet-to-be-developed standards. The current evolution of business applications through the continuing enhancement of web-enabled solutions will incorporate all the attributes of OLTP, batch, and data- intensive I/O. These application attributes will be key drivers in the SAN/NAS product evolution. Taken in context with current data-center infrastructures , the evolution of comprehensive SAN/NAS integrated products will definitely be a future solution.
As combined SAN/NAS solutions support the drive to an application democracy existing in a universal network, the integration of major components of the I/O infrastructure becomes paramount with the development of integrated and faster I/O protocols. This chapter discusses some of the key future technologies that will begin to affect IT storage networking solutions, along the way viewing future I/O infrastructure technologies from two perspectives. First will be a view external to the server with innovations such as iSCSI and InfiniBand. This will be followed by a view internal to the processor components with advancements such as HyperTransport and Rapid I/O initiatives.