Glossary C

C

capacity plan

Activities that identify business elements and translate these into workload requirements. These include the projection and configuration of systems that effectively process the workload requirements. Historically, capacity planning has included processor, memory, and storage capacity as a holistic system. However, storage networking separates the I/O workload from the computer systems and demands a new set of activities that estimate I/O workload but which are integrated back into the supported processor complex.

CD-ROM

Storage type that utilizes a polymer material for encoding information which is then subsequently read using a laser light source. CD-ROM has yet to be fully integrated into FC SAN; however, it can be used in some configurations with a SCSI bridge/router. CD-ROM drives are available as NAS devices and can be configured as network storage devices, with certain limitations.

cluster

In terms of computing, it's a collection of interconnected CPU resources that provide shared efficiencies, such as workload balancing, reliability, availability, and serviceability to the supporting infrastructure. In terms of storage, it's the smallest addressable unit on a disk drive as used by Windows operating systems. Cluster sizes are dependent on the total storage capacity of the disk-therefore, the larger the disk, the larger the cluster. This has a direct relationship to the efficiency of the system's I/O. Writing a single file to a large cluster uses the entire cluster. Consequently, writing a 1k file to a 32k cluster utilizes the entire space.

Common Internet File System (CIFS)

A distributed file system used with Windows operating environments that allows files to participate within networked file systems and network attached storage. CIFS has become an ad hoc standard in enabling Windows clients to participate and share files within networked environments.

controller

A device which controls and manages multiple devices that communicate with a computer system. Storage systems utilize controllers extensively to control and manage multiple storage devices that communicate within a bus system.

CPU

The central processing unit (CPU) is the mechanism that processes instructions which invoke all other actions within the computer and ultimately produce the results of the end- user application. The CPU is dependent on its basic architecture in how it operates and processes instructions. Two popular architectures are the Reduced Instruction Set (RISC) and Complex Instruction Set (CISC). Each processes instructions differently; however, both utilize temporary locations, such as registers and system-level cache, and initiate I/O operations.

cylinder

A measurement of disk geometry, where the association of tracks is measured vertically within the multiple platters of a disk drive. Cylinder allocations can have significant performance benefits for applications that access large amounts of information on a read-only basis.