NAS devices form an effective Network I/O manager for remote applications. From the perspective of the NAS hardware, functioning as an I/O manager, careful consideration should be given to the components and their corresponding characteristics that provide this complex functionality. This chapter will discuss NAS hardware components and their characteristics along with the issues that will confront these elements. Within these discussions will be definitions of key hardware components of the NAS device, configuration and capacities , and typical NAS I/O workloads as they relate to NAS hardware.
NAS hardware working in conjunction with related components function as an I/O manager. The NAS hardware components described in this chapter are the processor elements, RAM and related buffer management, and, of course, the storage system elements. We cannot overlook the communications and input-processing components largely made up of NIC interface elements and related bus connectivity options. These elements will be described and discussed in Chapter 12, which deals with NAS connectivity options, but it is important to recognize them in relation to the NAS hardware.
Closely related to NAS hardware are the effects of NAS processing models. Three models of NAS processing exist which drive NAS configurations and related component capacities:
Simple extensions of a clients file system, as a shared storage resource, make up simple file processing (Sfp).
Remote file acquisition with added reliability from a heterogeneous set of clients constitute quality file processing (Qfp).
Enterprise-level processing of files using NAS within a transactional type of system with heterogeneous access and multitier applications form a complex file processing (Cfp) configuration.
With the NAS hardware functioning as an I/O manager, the performance of its components will be characterized by the workloads it processes. NAS workloads are made up of file-oriented processing activities performed on behalf of various applications. These workloads consist of I/O operations with disparate I/O content. Client network files transferring office application files offer a dramatically different I/O content contrasted against the unstructured data such as image, video, and audio. On the other hand, web-based and other specialized application file structures exhibit everything from variable length files to compressed and encryption-encapsulated, structures.