HP Surestore Disk Array 12h - And FC60, Advanced User'S Manual, Page: 65 / 466

Capacity Management Features
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Capacity Management Features
The disk array uses a number of features to manage its disk capacity efficiently. The use of
LUNs allow you to divide the total disk capacity into smaller, more flexible partitions.
Caching improves disk array performance by using controller RAM to temporarily store
data during I/Os.
Note Differences in HP-UX and Windows NT/2000 Capacity Management
Capacity management on Windows NT and Windows 2000 offers some unique
features. Refer to the HP Storage Manager 60 Introduction Guide for
information on Windows-specific features. Some of the terms used in the HP
Storage Manager 60 software differ from those used here. These terms are also
listed in the HP Storage Manager 60 Introduction Guide.
LUNs
The capacity of the disk array can be divided into entities called LUNs. Individual disks are
grouped together to form a LUN. Functionally, each LUN appears to the host operating
system as an individual disk drive.
Although the LUN appears to the host as an individual disk, the use of multiple disks offers
advantages of increased data availability and performance. Data availability is enhanced by
using redundant data stored on a separate disk from the original data. The use of multiple
disks increases performance by allowing simultaneous access to several disks when
reading and writing data.
Disk Groups
A disk group is a collection of individual disks that share a common role in disk array
operation. All disks on the disk array become a member of one of the following disk
groups:
•
LUN group – Each LUN on the disk array has its own disk group. When a disk is included
as part of a newly created LUN, the disk becomes a member of the associated disk
group. There can be only one LUN in each LUN disk group.