HP XP7 Storage - Manual (Page 5)

1 Overview
This topic provides an overview of Parallel Access Volumes (PAV).
About Parallel Access Volumes
The Parallel Access Volumes (PAV) feature enables an IBM zSeries or S/390® host system to issue
multiple I/O requests in parallel to individual logical devices (LDEVs) in the HP XP7 Storage system.
For more information on the zSeries and S/390 PAV host software feature, see the following IBM
documents:
•
DFSMS/MVS Software Support for IBM Enterprise Storage Server, SC26–7318
•
DS8000 Performance Monitoring and Tuning, SG24–7146
•
System/390® Command Reference 2105 Models E10, E20, F10, F20, SC26-7298
Devices used in PAV operations
The two device types used in PAV operations are base devices and alias devices:
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Base devices
A base device is an installed and formatted device (for example, 3390-9) that contains user data.
A base device must be defined to the host as a “B” device type (for example, 3390B-9).
CAUTION: The following volumes cannot be defined as base devices:
•
Journal volumes for Continuous Access Journal Z
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Data Exchange volumes
•
Migration volumes
Alias devices
An alias device is a formatted but unassigned logical device whose LDEV ID (address) can be used
as an alias for a base device. Alias devices cannot be varied online. Each alias must be within
the same logical CU image as the base device to which it is assigned. Base and alias devices are
defined to the host OS using a combination of HCD/IODF/IOCDS. An alias device must be defined
to the host as an “A” device type (for example, 3390A-9).
For more information about defining base and alias devices to operating systems, see (page 14) .
Parallel Access Volumes modes
Parallel Access Volumes operations can be performed in one of two standard operational modes.
The Parallel Access Volumes mode is controlled by the Dynamic alias management parameter
setting for the IBM Workload Manager® (WLM) and the WLMPAV parameter setting in the HCD
file.
HP Confidential About Parallel Access Volumes 5