XP10000 (HITA737-96003, March 2007)

HPAV for z/OS user guide for the XP128/XP1024/XP12000/XP10000 9

1 HPAV for the XP1024/XP128/XP12000/XP10000

HPAV (Hitachi Parallel Access Volume) enables a zSeries® and S/390® host system to issue multiple I/O

requests in parallel to logical devices (LDEVs) on an XP1024/XP128/XP12000/XP10000. When HPAV 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. HPAV allows the host system to start

multiple I/O requests to the same device at the same time through the alias addresses assigned to a

device. When HPAV is used, the zSeries and S/390 host computer has substantially faster access to the

data stored in the XP1024/XP128/XP12000/XP10000.

The two types of devices used in HPAV operations are base devices and alias devices. The base devices

are the installed devices that contain user data. The alias devices are installed but are unused devices

whose addresses can be used as aliases for the base devices. The XP1024/XP128/XP12000/XP10000

supports up to 256 devices per logical control unit (CU), including base and alias devices, for a maximum

of 65,280 device addresses per disk array.

HPAV on the Command View XP management station or XP Remote Web Console configures HPAV devices

on the XP1024/XP128/XP12000/XP10000, such as assigning aliases to base devices, canceling aliases,

and so forth. The Command View XP management station or XP Remote Web Console is attached to and

communicates directly with the XP1024/XP128/XP12000/XP10000 through the LAN.

The Workload Manager (WLM) host software function enables the zSeries and S/390 host to use the

HPAV functionality of the XP1024/XP128/XP12000/XP10000. WLM compatibility mode provides static

HPAV functionality and WLM goal mode provides dynamic HPAV functionality. The

XP1024/XP128/XP12000/XP10000 supports both static and dynamic HPAV. When static HPAV is used,

the number of aliases assigned to each base device does not change. For dynamic HPAV, the number of

aliases assigned to a base device can change depending on the number of host I/O requests to that

device. For more information on static and dynamic HPAV, see ”Static and Dynamic HPAV Operations” on

page 12.

Overview of HPAV Operations

Components

The components that are involved in HPAV operations are:

• Base devices and alias devices on the disk array (see page 9)

• Controller emulation type for the disk array (see page 10)

• HPAV software enabled on the disk array through the Command View XP management station or XP

Remote Web Console (see Managing license keys and/or Command View-based HPAV in the

HP StorageWorks Command View XP User Guide for XP Disk Arrays or the HP StorageWorks XP

Remote Web Console User Guide for the specific disk array)

• Hardware Configuration Definition (HCD) definitions for the disk array (see page 10)

• WLM host software definitions for dynamic alias management (see page 10)

Base Devices and Alias Devices

The XP1024/XP128/XP12000/XP10000 supports a maximum of 65,280 logical devices (LDEVs), up to

256 LDEVs per logical control unit (CU) image and up to 255 CU images. The number of LDEVs per parity

group depends on the hard disk drive (HDD) type, RAID level, and device emulation type (for example,

3390-3R) of the parity group. Each LDEV is uniquely identified by its LDEV ID, which consists of the logical

CU image number (0, 1, 2...FE) and device number (00-FF hexadecimal) (for example, x0:0F = device 0F

in CU image 0).

LDEVs that are formatted as zSeries and OS/390® devices (for example, 3390 or 3380) are called

logical volume images (LVIs) or volumes. LDEVs formatted as open system devices (for example, OPEN-3 or

OPEN-9) are called logical units (LUs). HPAV operations can be performed only on 3390 LVIs.