IBM 86655RY - Netfinity 7600 - 8665, Руководство по техническому обслуживанию аппаратной части

Страница: 202 / 294

192
Hardware Maintenance Manual: Netfinity 7600 – Type 8665 Models 1RY, 2RY
Reference information
This section contains information to help you understand the principles and uses of
high-performance, redundant array of independent disk (RAID) controllers. This
section describes the different ways that drives can be grouped together to create
data-storage environments that require superior performance, flexibility, and reliable
data storage. A listing of important acronyms, terms, and definitions is also included
at the end of this section.
Understanding RAID technology
RAID is the technology of grouping several physical drives in a computer into an
array that you can define as one or more logical drives. Each logical drive appears to
the operating system as a single drive. This grouping technique greatly enhances
logical-drive capacity and performance beyond the physical limitations of a single
physical drive.
When you group multiple physical drives into a logical drive, the ServeRAID
controller can transfer data in parallel from the multiple drives in the array. This
parallel transfer yields data-transfer rates that are many times higher than with
nonarrayed drives. This increased speed makes the system better able to meet the
throughput (the amount of data processed in a given amount of time) or productivity
needs of the multiple-user network environment.
The ability to respond to multiple data requests provides not only an increase in
throughput, but also a decrease in response time. The combination of parallel
transfers and simultaneous responses to multiple requests allows disk arrays to
provide a high level of performance in network environments.