HP XP Array Manager Software - Manual (Page 5)

1 About LUSE Operations
This chapter gives an overview of HP StorageWorks LUN Expansion (LUSE) operations:
• Overview of LUN Expansion (LUSE)
•
LUSE Function
•
LUSE Guidelines
Overview of LUN Expansion (LUSE)
LUN Expansion (LUSE) operations allow hosts that can use only a limited number of logical units
(LUs) per fiber optic interface to have access to larger amounts of data by using expanded LUs.
LUSE Function
LUN Expansion (LUSE) is a function for open systems. To use this function, you need the software
called Open Volume Management.
The LUSE function is applied to open-system logical volumes and enables you to configure one
large logical volume by combining several small logical devices (LDEVs). The LUSE function allows
hosts that can use only a limited number of LUs per fiber optic interface to have access to larger
amounts of data by using expanded LUs.
“LUSE Configuration” (page 5) shows the LUSE configuration. By using the LUSE function, you
can combine several LDEVs or volumes into one large logical volume. Up to 36 LDEVs can be
combined. The ID of the logical volume defined as the large logical volume is represented by the
smallest LDEV ID (assigned to the top LDEV). The host recognizes the expanded logical volume as
one representative LDEV. As long as the number of LDEVs combined into one large logical volume
does not exceed the specified limit (see
“Specifications and Restrictions on LDEVs Used to Configure
a LUSE Volume” (page 6) ), you can arbitrarily select any LDEVs as the volumes to combine,
regardless of their size (or capacity) or whether or not they are on the same Control Unit (CU).
The LUSE function also allows you to combine several LDEVs and a LUSE volume (combined LDEVs)
into one LUSE volume, or combine LUSE volumes together into one LUSE volume.
Before the host can access each LDEV composing an expanded LU (LUSE volume), you must release
the expanded LU.
Figure 1 LUSE Configuration
Overview of LUN Expansion (LUSE) 5