HP StorageWorks XP Remote Web Console Software - Manual (Page 5)

1 Overview of HP StorageWorks XP for Compatible Parallel
Access Volumes Software
This chapter provides an overview of how Compatible PAV operates and the interactions it has
with other software.
Compatible PAV has the following two capabilities:
•
Compatible PAV function
•
HP StorageWorks XP Compatible Hyper PAV function
The Compatible PAV feature itself has two unique capabilities as shown next:
•
Static Compatible PAV
•
Dynamic Compatible PAV
In this guide, Compatible PAV and XP Compatible Hyper PAV are collectively referred to as
Compatible PAV, unless otherwise noted.
The term storage system in this guide refers to an HP StorageWorks XP24000 disk array.
The GUI illustrations in this guide were created using a Windows computer with the Internet Explorer
browser. Actual windows may differ depending on the operating system and browser used. GUI
contents also vary with licensed program products, storage system models, and firmware versions.
About Compatible PAV Feature
The Compatible PAV feature enables a single zSeries and S/390 host system to issue multiple I/O
requests in parallel to individual logical devices (LDEVs) in the HP storage system. When Compatible
PAV is not used, the host system can start only one I/O request to a device at a time, and must
wait for the I/O to complete before starting another I/O request to the same device. Compatible
PAV enables the host system to start multiple I/O requests to the same device at the same time via
alias addresses assigned to a device. When Compatible PAV is used, the zSeries and S/390 host
computer has substantially faster access to the data stored in the storage system.
The two types of devices used in Compatible PAV operations are base devices and alias devices.
The base devices are the formatted devices which contain user data. The alias devices are defined
but not installed devices whose addresses can be used as aliases for the base devices. The storage
system supports up to 256 devices per Logical Control Unit (LCU), including base and alias devices,
for a maximum of 130,560 device addresses (base + aliases) per subsystem.
The licensed Compatible PAV on the HP StorageWorks Remote Web Console computer allows
you to configure Compatible PAV devices on the storage system (that is, assign aliases to base
devices, cancel aliases). The Remote Web Console computer is attached to and communicates
directly with the storage systems via the storage system internal private LAN. For further information
on the Remote Web Console computer, see the HP StorageWorks XP24000/XP20000 Remote
Web Console User Guide.
The Workload Manager (WLM) host software function enables the zSeries and S/390 host to
utilize the Compatible PAV functionality of the storage system. WLM compatibility mode provides
static Compatible PAV functionality, and WLM goal mode provides dynamic Compatible PAV
functionality. The storage system supports both static and dynamic Compatible PAV. When static
Compatible PAV is used, the number of aliases assigned to each base device does not change.
For dynamic Compatible PAV, the number of aliases assigned to a base device can change
depending on the number of host I/O requests to that device. See
“Static and Dynamic Compatible
PAV Operations” (page 11) for further information on static and dynamic Compatible PAV.
About Compatible PAV Feature 5