Overview; About Parallel Access Volumes; Devices Used In Parallel Access Volumes Operations; Base Devices - HPE XP7 User Manual

Overview

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 XP7 Storage (XP7) system.

Devices used in Parallel Access Volumes operations

The two device types used in Parallel Access Volumes operations are base devices and alias devices:
•

Base devices

•

Alias devices

XP7 supports up to 256 devices per CU (control unit).
Base and alias devices are defined to the host OS using a combination of HCD/IODF/IOCDS.
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). Base devices are defined
by the storage system when the mainframe emulated volumes are defined and installed.
CAUTION: The following volumes cannot be defined as base devices:
• Journal volumes for Continuous Access Journal MF
• Migration volumes
A Data Exchange volume is defined as a base, but a Data Exchange volume cannot use Parallel Access
Volumes.
More information
Defining base or alias devices to host operating systems on page 24
Alias devices
An alias device is an LDEV ID (address), where no actual LDEV is defined in the storage system, that can
be used with the defined base addresses in the same CU to issue parallel requests to a base address
that already has one or more active I/Os in process. Alias devices cannot be varied online. Each alias
must be in the same logical CU image as the base device to which it is assigned. An alias device must be
defined to the host as an "A" device type (for example, 3390A). To use alias devices, they must be
configured in the storage system using Remote Web Console.
More information
Defining base or alias devices to host operating systems on page 24

Parallel Access Volumes modes

Parallel Access Volumes operations can be performed in one of four operational modes (dynamic, static,
Hyper Parallel Access Volumes, or Compatible Super PAV). The Parallel Access Volumes mode is
6 Overview