IBM Enterprise Storage Server 2105 E10, Introduction And Planning Manual

Page: 15 / 156

About this guide
This publication introduces the IBM
®
Enterprise Storage Server
™
(ESS) and lists
the features you can order. It also gives guidelines for the following tasks:
v
Planning for installation
v
Planning communications
v
Planning data migration
Who should use this guide
This publication is for storage administrators, system programmers, and
performance and capacity analysts.
Frequently used terms
The following terms appear in this publication to describe the IBM Enterprise
Storage Server (ESS) and its configuration. Also see the “Glossary” on page 107 for
additional terms and definitions.
Term Definition
array An arrangement of related disk drive modules
(DDMs) that you have assigned to a group. Also
referred to as a rank. For the ESS, an array is a
group of up to eight DDMs.
cluster A partition of a storage server that is capable of
performing all functions of a storage server. When a
cluster fails in a multiple-cluster storage server, the
cluster that remains in the configuration takes over
the processes of that cluster.
controller image A System/390
®
term for a logical subsystem that
you access with an ESCON
®
I/O interface. One or
more controller images exist in each controller.
Each image appears to be an independent
controller, but all images share a common set of
hardware facilities. The ESS can emulate 3990-3,
3990-6, or 3990-3 TPF controller images.
count key data (CKD) A System/390 term for a logical device that
specifies the format of the logical data units on the
device. The logical data unit is a track that contains
one or more records, consisting of a count field, a
key field (optional), and a data field (optional).
device adapter A physical component of a storage controller that
attaches to one or more interfaces. It enables
communication between the interfaces and the
associated storage devices.
destage The process of writing modified storage from cache
to the disk drive module (DDM).
disk drive module (DDM) The primary, nonvolatile storage medium that you
use for any host data that is stored within a storage
server. The number and type of storage devices
within a storage server may vary.
© Copyright IBM Corp. 1999, 2000
xiii