HP StorageWorks XP Remote Web Console Software User Manual

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

Compatible PAV Function for the

XP1024/XP128/XP12000/XP10000

Compatible PAV (Hitachi Parallel Access Volume) function 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 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 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 Compatible PAV 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 Compatible PAV operations are base devices and alias devices. The base

devices are the physically installed and formatted volumes in a logical control unit (maximum 256) that can

contain data. The alias devices are the volumes that are not physically installed in the same logical control

unit (alias = 256 - base). Every logical controller can support up to 256 devices. The maximum number of

these Logical Control Units (or LCU's) per XP depend upon the XP model.( for XP12K, 255 LCU's; for

XP10K, 64 LCU's for XP1024 and XP128 32 LCU's)
Compatible PAV on the Command View XP management station or XP Remote Web Console configures

Compatible PAV 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 a

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

Compatible PAV functionality of the XP1024/XP128/XP12000/XP10000. WLM compatibility mode

provides static Compatible PAV functionality and WLM goal mode provides dynamic Compatible PAV

functionality. The XP1024/XP128/XP12000/XP10000 can support static or dynamic compatible PAV (the

XP12K/10K also Hyper 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 and the goals as

they were defined in the WLM. For more information on static and dynamic Compatible PAV, see ”