HPE XP7 Automation Director User manual

HPE XP7 for Compatible Parallel Access
Volumes User Guide
Part Number: 858770-004
Published: June 2019
Edition: 8
Abstract
This guide describes and provides instructions for performing Parallel Access Volumes
operations on XP7 Storage system. This document is intended for system administrators and
Hewlett Packard Enterprise representatives and authorized service providers who install,
configure, and operate the XP7 Storage system.

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Contents
Overview.................................................................................................. 6
About Parallel Access Volumes.................................................................................................... 6
Devices used in Parallel Access Volumes operations.................................................................. 6
Base devices......................................................................................................................6
Alias devices...................................................................................................................... 6
Parallel Access Volumes modes...................................................................................................6
Parallel Access Volumes in dynamic mode........................................................................7
Parallel Access Volumes in static mode.............................................................................8
Workload Manager........................................................................................................................8
WLM in goal mode............................................................................................................. 9
WLM in compatibility mode................................................................................................ 9
Hyper Parallel Access Volumes.................................................................................................... 9
Compatible Super PAV..................................................................................................................9
I/O request workflow using Parallel Access Volumes................................................................... 9
I/O request workflow using Hyper Parallel Access Volumes.......................................................10
I/O request workflow using Compatible Super PAV.................................................................... 11
Requirements and specifications........................................................13
Requirements..............................................................................................................................13
Functions incompatible with Parallel Access Volumes............................................................... 15
Parallel Access Volumes shared across multiple sysplexes.......................................................15
Considerations for using Compatible Super PAV........................................................................15
Performance design of Compatible Super PAV................................................................15
Cautions on using Compatible Super PAV....................................................................... 16
Restrictions on using Compatible Super PAV.................................................................. 18
Defining devices....................................................................................19
Unused device addresses usage as alias devices..................................................................... 19
Optimal Parallel Access Volumes results and base-to-alias device ratios....................... 19
Optimal dynamic PAV results and alias devices...............................................................19
Hyper Parallel Access Volumes optimum base/alias device ratio....................................19
Compatible Super PAV optimum base/alias device ratio................................................. 19
Defining logical control units....................................................................................................... 20
Defining base or alias devices to host operating systems.......................................................... 24
Finding a device eligible for dynamic Parallel Access Volumes management............................29
Address mapping between base and alias devices.................................................................... 34
Preparing for Parallel Access Volumes operations........................... 35
Setting the WLM operational mode.............................................................................................35
Enabling the Super PAV mainframe system function .................................................................37
Hyper Parallel Access Volumes enablement from z/OS on z/VM workflow................................37
Enabling Hyper Parallel Access Volumes on z/OS.......................................................... 38
Enabling Hyper Parallel Access Volumes from z/OS on z/VM.........................................38
Enabling Compatible Super PAV on z/OS...................................................................................39
MIH timer value setting workflow................................................................................................ 39
Contents 3

Performing Parallel Access Volumes operations.............................. 40
Assigning alias volumes to base volumes.................................................................................. 40
Deleting alias volumes from base volumes.................................................................................42
Assigning alias volumes to different base volumes.....................................................................44
Calculating Parallel Access Volumes used capacity...................................................................45
Verifying and monitoring devices........................................................47
Verifying the device definitions....................................................................................................47
Verifying the status of devices per channel path.........................................................................48
Verifying Hyper Parallel Access Volumes aliases from z/OS......................................................49
Verifying Hyper Parallel Access Volumes aliases from z/OS on z/VM........................................49
Sample of commands run to all base devices and alias devices from z/VM.............................. 50
MVS commands to monitor Parallel Access Volumes................................................................ 51
DISPLAY command..........................................................................................................51
DEVSERV PATHS command...........................................................................................52
DEVSERV QPAV commands........................................................................................... 52
DISPLAY IOS HYPERPAV command.............................................................................. 56
GTF I/O tracing........................................................................................................................... 56
VM CP commands for z/VM........................................................................................................56
QUERY CU command......................................................................................................57
QUERY DASD DETAILS command................................................................................. 58
QUERY PAV command.................................................................................................... 58
QUERY VIRTUAL DASD DETAILS command.................................................................58
QUERY VIRTUAL PAV command.................................................................................... 59
Troubleshooting.................................................................................... 60
General troubleshooting..............................................................................................................60
Discontinuing HyperPAV and SuperPAV.............................................61
Disabling HyperPAV from z/OS...................................................................................................61
Disabling SuperPAV from z/OS...................................................................................................61
Disabling HyperPAV from z/OS when using multiple storage systems....................................... 62
Disabling SuperPAV from z/OS when using multiple storage systems....................................... 62
Disabling HyperPAV from z/OS on z/VM.....................................................................................63
Parallel Access Volumes GUI reference............................................. 65
Parallel Access Volumes window................................................................................................65
Base Volume List............................................................................................................. 66
Alias Volume List..............................................................................................................67
Free Volume List.............................................................................................................. 67
Edit Mainframe System Functions wizard...................................................................................67
Edit Mainframe System Functions window...................................................................... 67
Edit Mainframe System Functions confirmation window..................................................69
Websites................................................................................................ 72
Support and other resources...............................................................73
Accessing Hewlett Packard Enterprise Support......................................................................... 73
4Contents

Accessing updates......................................................................................................................73
Customer self repair....................................................................................................................74
Remote support.......................................................................................................................... 74
Warranty information...................................................................................................................74
Regulatory information................................................................................................................75
Documentation feedback............................................................................................................ 75
Warranty information............................................................................76
Regulatory information................................................................................................................76
Contents 5

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

controlled by the Dynamic alias management parameter setting for the IBM® Workload Manager® (WLM)
and the WLMPAV parameter setting in the HCD file.
The XP7 Storage system uses the I-2107 control unit emulation. You can use one of the following modes:
• Dynamic Parallel Access Volumes mode
For more information about this mode, see Parallel Access Volumes in dynamic mode on page
7.
• Static Parallel Access Volumes mode
For more information about this mode, see Parallel Access Volumes in static mode on page 8.
• Hyper Parallel Access Volumes (HPAV) mode
You can specify the PAV feature (Parallel Access Volumes, Hyper Parallel Access Volumes, or
Compatible Super PAV) to use for each host computer. Therefore, an alias device may accept I/O
requests from PAV, HyperPAV, or SuperPAV.
For more information about this mode, see Hyper Parallel Access Volumes.
• Compatible Super PAV (Super PAV) mode
You can specify the PAV feature (Parallel Access Volumes,Hyper Parallel Access Volumes, or
Compatible Super PAV) to use for each host computer. Therefore, an alias device might accept I/O
requests from PAV, and I/O requests from HyperPAV and SuperPAV. For more information about this
mode, see Compatible Super PAV on page 9.
For more information:
• About WLM, see Workload Manager and Setting the WLM operational mode.
• About the WLMPAV parameter and HCD file, see Parallel Access Volumes in dynamic mode on
page 7.
Parallel Access Volumes in dynamic mode
In Parallel Access Volumes dynamic mode, the number of alias devices assigned to each base device
may dynamically increase or decrease based on the number of I/O requests to each device. Dynamic
mode assists in balancing workloads on base devices and can optimize the speed of accessing data in
the XP7 Storage. A dynamic Parallel Access Volumes operation is implemented when the WLM feature
for Dynamic alias management setting and the WLMPAV parameter setting in the HCD file are both set to
Yes.
For more information about setting the WLM operational mode, see Setting the WLM operational mode.
In the following figure, the x10, x11, and x12 base devices were originally assigned two alias devices
each. In this example, as I/O requests converge on the base device x10 (indicated by the large arrow),
the number of alias devices for base device x10 increases to four, while the number of alias devices
assigned to the base devices x11 and x12 decreases to one each.
Parallel Access Volumes in dynamic mode 7

Parallel Access Volumes in static mode
In Parallel Access Volumes static mode, the number of alias devices assigned to each Parallel Access
Volumes base device remains the same, even when the number of I/O requests to each device changes.
To use static Parallel Access Volumes, set the WLM operational mode to compatibility mode. The WLM
operational mode must be set to compatibility mode to support static Parallel Access Volumes operations.
While in compatibility mode, WLM manages the system according to parameters in IPS and ICS
(IEAIPSxx and IEAICSxx parmlib members).
For more information about setting the WLM operational mode, see Setting the WLM operational mode.
The following figure shows an example of Parallel Access Volumes base devices assigned to alias
devices.
In this example, the x10, x11 and x12 base devices were originally assigned two alias devices each. As
I/O requests converge on the base device x10 (indicated by the large arrow), the number of alias devices
for each base device does not change.
Workload Manager
The host computer uses WLM for Parallel Access Volumes. It is a software component of the IBM
MVS/ESA and z/OS operating systems.
8 Parallel Access Volumes in static mode

WLM supports dynamic and static Parallel Access Volumes operations and manages workloads using
one of the following operational modes:
• Goal mode
For more information about this mode, see WLM in goal mode.
• Compatibility mode
For more information about this mode, see WLM in compatibility mode.
WLM in goal mode
The WLM must be in goal mode to support dynamic Parallel Access Volumes operations. The WLM is in
goal mode when the Dynamic alias management setting in the WLM Service Coefficient/Service
Definition Options screen is set to Yes. While in goal mode, the WLM manages the system to meet a
performance goal.
WLM in compatibility mode
The WLM must be in compatibility mode to support static Parallel Access Volumes operations. The WLM
is in compatibility mode when the Dynamic alias management setting in the WLM Service Coefficient/
Service Definition Options screen is set to No. While in compatibility mode, the WLM manages the
system according to parameters in IPS and ICS (IEAIPSxx and IEAICSxx parmlib members).
Hyper Parallel Access Volumes
You can use the Hyper Parallel Access Volumes feature to map an entire collection of alias devices to a
single Parallel Access Volumes base device in a CU and to have all other base devices in the same CU
share these aliases.
The HPAV feature does not require that you change the number of alias devices assigned to each base
device. With the Hyper Parallel Access Volumes feature, a whole collection of alias devices can be
mapped to one base device in a CU when configuring the aliases using Remote Web Console in the
storage system.
You can specify the PAV feature (Parallel Access Volumes or Hyper Parallel Access Volumes) to use for
each host computer. Therefore, an alias device may accept I/O requests from Parallel Access Volumes or
Hyper Parallel Access Volumes.
Compatible Super PAV
The Hyper Parallel Access Volumes feature enables you to map alias devices to base devices only within
the same CU. If you want to map alias devices in a different CU, you must enable the Super PAV
mainframe system function on the storage system. When the Super PAV mainframe system function is
enabled, you can map an entire collection of alias devices to a single base device that is in a different CU.
You can specify the PAV feature (Parallel Access Volumes, Hyper Parallel Access Volumes, or
Compatible Super PAV) to use for each host computer. Therefore, an alias device might accept I/O
requests from Parallel Access Volumes, Hyper Parallel Access Volumes, and Compatible Super PAV.
I/O request workflow using Parallel Access Volumes
Multiple alias devices are assigned to a base device in a CU to enable the base device to handle multiple
I/O requests.
The existence of defined aliases devices allows the operating system to issue parallel I/Os by issuing I/O
to the base address and associated alias addresses for the base device. The maximum number of
WLM in goal mode 9

parallel I/Os is the number of aliases assigned to the base plus 1 for static or dynamic configurations.
When HPAV is used, the maximum number of parallel I/Os to a base address is the number of aliases
configured in the CU plus 1. If multiple base devices are using aliases, the maximum number for any
individual base device is reduced accordingly.
In the following figure, three alias devices are each assigned to base devices 1, 2 and 3.
As illustrated with the arrows in the figure, I/O requests converge on base device 1 when a host computer
accesses the device using Parallel Access Volumes. Since alias devices A, B, and C were assigned to
base device 1 in advance of the operation, I/O requests are automatically issued to these alias devices.
Similarly, if a host computer accesses base devices 2 and 3, the I/O requests are automatically issued to
the alias devices assigned to those two base devices. Base device 4 is not able to process multiple I/O
requests since an alias device is not assigned to the device.
I/O request workflow using Hyper Parallel Access Volumes
Multiple alias devices are assigned to a base device in a CU to enable the base device to handle multiple
I/O requests. In HPAV, alias devices are pooled together in each CU. All base devices in the CU share
the alias devices as a pool. The aliases are assigned to a specific base address for the duration of the I/O
and then returned to the alias pool for the CU.
In the following figure, three alias devices each are assigned to base devices 1, 2, and 3.
10 I/O request workflow using Hyper Parallel Access Volumes

As illustrated with the arrows in the figure, I/O requests converge on base device 1 when a host computer
accesses the device using PAV. I/O requests are automatically issued to unused alias devices among the
nine alias devices in the CU.
Similarly, if a host computer accesses base devices 2, 3, and 4, the I/O requests are automatically issued
to unused alias devices among the nine alias devices. Base device 4 can process multiple I/O requests
even though an alias device was not specifically assigned to the device when the aliases were configured
with Remote Web Console.
I/O request workflow using Compatible Super PAV
Multiple alias devices are assigned to a base device in a CU to enable the base device to handle multiple
I/O requests. With the Super PAV feature, alias devices are grouped into an alias management group
(AMG) and pooled. All base devices in a CU can share alias devices in the AMG. In addition, an AMG
contains alias devices across CUs, therefore, a base device can use alias devices in different CUs.
When the Super PAV feature is enabled, two AMGs (an AMG for odd numbered CUs and an AMG for
even numbered CUs) are created automatically. A base device can use only alias devices in the AMG to
which alias devices in the same CU belong. The host computer allocates alias devices in the same CU as
the base device if they are available. This I/O processing is handled by HPAV. If the host cannot allocate
alias devices in the same CU, it allocates alias devices in another CU within the AMG. This I/O
processing is handled by Super PAV.
In the following figure, three alias devices each are allocated to base devices 1, 2, and 3. As illustrated
with the arrows in the figure, I/O requests converge on base device 1 when a host computer accesses the
device using Super PAV. The I/O requests are automatically issued to unused alias devices among the
six alias devices A through F in the same CU of the AMG. If the six alias devices cannot be used or are
not sufficient, alias devices G through I in another CU within the AMG can be used.
Although no alias device is allocated to base device 4, multiple I/O requests can be processed. Alias
devices G through I in the same CU are allocated first, and then alias devices A through F in another CU
are allocated if necessary.
The following figure illustrates I/O accesses using Super PAV.
I/O request workflow using Compatible Super PAV 11

12 Overview

Requirements and specifications
This topic contains requirements and specifications.
Requirements
The following table lists the requirements for PAV, HPAV, and Super PAV operations.
Item Requirements
PAV HPAV Super PAV
Software License Keys PAV
Workload Manager (WLM)
PAV
HPAV
Workload Manager (WLM)
Host OS Dynamic mode: z/VM5.2
with PTF or later
Static mode: VM/ESA2.4.0
or later
z/OS 1.8 or later
z/OS 1.6 with PTF or
later
z/TPF OS 1.1 with
APAR PJ41092 or later
z/VM 5.3 or later
When you use z/VM,
you must use z/OS or
z/TPF as a guest OS
on z/VM.
z/OS 2.2 or later with
PTF containing APAR
OA56359
Controller emulation
type
I-2107 I-2107 or I-2107-TPF I-2107
Device emulation type
for base device
3390-1, 3390-2, 3390-3, 3390-9, 3390-L, 3390-M, 3390-A
Data Exchange devices listed below are not supported:
3390-3A, 3390-3B, 3390-3C
3390-9A, 3390-9B, 3390-9C, 3390-LA, 3390-LB, 3390-LC
3390-MA, 3390-MB, 3390-MC
For PAV and HPAV, all devices including supported device emulation types do
not operate in a CU that contains any of the above device emulation types
which are online.
For HPAV and the z/TPF OS, only the device emulation types listed below are
supported:
3390-3, 3390-9, 3390-L, 3390-M
For Super PAV, Compatible Super PAV cannot be used on the storage system
that has a CU in which both devices with Data Exchange and other devices
with mainframes are defined. For more information, see Restrictions on
using Compatible Super PAV on page 18.
Table Continued
Requirements and specifications 13

Item Requirements
PAV HPAV Super PAV
Channel interface FICON
Storage system ID
setting
One storage system ID for each set of 256 LDEVs
Maximum number of
aliases for one base
device
255
Alias device
management
Alias device and its base device must belong to the same logical CU image.
For Super PAV, alias devices are grouped into odd numbered CUs and even
numbered CUs. A base device can also use alias devices in different CUs in
the group to which alias devices in the same CU belong.
Remote Web Console PAV and HPAV need the Remote Web Console secondary window. To use the
Remote Web Console secondary window, install JRE and set up Java, see the
chapter about how to use the Remote Web Console secondary window in the
HPE XP7 Remote Web Console User Guide.
Compatible functions • Virtual LVI
• Cache Residency MF
• Auto LUN
• Continuous Access Synchronous MF
• Business Copy MF
• Continuous Access Journal MF
• IBM Concurrent Copy (CC) with restrictions
• Compatible XRC with restrictions
• PPRC
• Thin Provisioning MF
• Smart Tiers MF
• Real Time Smart Tier for Mainframe
For z/TPF OS, only the functions listed below can be used:
• Virtual LVI
• Cache Residency MF
• Business Copy MF
• Continuous Access Synchronous MF
• Continuous Access Journal MF
14 Requirements and specifications

Functions incompatible with Parallel Access Volumes
Devices using Parallel Access Volumes, Hyper Parallel Access Volumes, or Compatible Super PAV
cannot be used concurrently with the following functions:
• Data Exchange
• Open Volume Management
• Cache Residency
• Business Copy (open system version)
• Continuous Access Synchronous (open system version)
• Continuous Access Journal (open system version)
• High Availability
The devices using any function other than Data Exchange of the functions listed above can coexist in the
same CU with devices using Parallel Access Volumes, Hyper Parallel Access Volumes, or Compatible
Super PAV. However, the devices using Data Exchange cannot coexist in the same CU with devices
using Parallel Access Volumes, Hyper Parallel Access Volumes, or Compatible Super PAV.
Parallel Access Volumes shared across multiple sysplexes
You can share Parallel Access Volumes functionality across multiple sysplexes on a storage system.
To share static PAV, all connected systems must be in compatibility mode. To share dynamic PAV, the
following requirements and restrictions apply:
• Only one sysplex must be running in Dynamic Alias Management mode. This master sysplex is the
only sysplex connected to the storage system that assigns aliases.
• For all other connected sysplexes, set the WLMPAV (HCD) and Dynamic Alias Management (WLM)
settings to No.
NOTE: If you have enabled Dynamic Alias Management for more than one sysplex, unsynchronized alias
transition and unpredictable response times may occur.
For more information about setting the WLM mode, Setting the WLM operational mode.
Considerations for using Compatible Super PAV
When using Compatible Super PAV, the following performance design, cautions, and restrictions are
required.
Performance design of Compatible Super PAV
The Compatible Super PAV feature enables you to use alias volumes in a different CU from the one that
contains base volumes. Therefore, when Hyper Parallel Access Volumes is used, if you enable
Compatible Super PAV, the throughput performance improvement can be expected by increasing I/O
multiplicity. On the other hand, as the I/O multiplicity for base volumes increases, the load on the
processor and the amount of data per unit time against base volume might be increased. These might
cause the following effects:
Effects on using Compatible Super PAV:
Functions incompatible with Parallel Access Volumes 15

• Increase in the processor availability ratio and delay in the associated I/O processing (increase in the
amount of queuing time and response time).
• Suspend due to full journal volume caused by data inflow increase.
• Overload of the connection path between the primary and secondary storage systems.
In particular, in a system that contains a CU (a CU with a high IOSQ at all times) in which alias volumes
are always depleted, using Compatible Super PAV causes the increase in the load on the system, and
therefore the system balance might be lost. Make sure that there are no high load portions (such as the
processor availability ratio or the path between the primary and secondary storage systems) before
enabling Compatible Super PAV.
When Compatible Super PAV is newly installed, we recommend to define required alias volumes in its CU
as with Hyper Parallel Access Volumes. Alias volumes are grouped into even numbered CUs and odd
numbered CUs, and only aliases in the same group can be shared. Therefore, make sure to design the
appropriate number of alias volumes in order to avoid being biased by considering the number of base
volumes in even numbered CUs and odd numbered CUs, and the assumed multiplicity.
In the configuration where the number of alias volumes in its CU is minimized and alias volumes are
collectively defined in several CUs as pools, many I/Os use alias volumes in different CUs. In this case,
you cannot manage how the host computer assigns alias volumes to many I/O operations to be
performed. Therefore, we recommend to design alias volumes as much as possible based on the
operations with Hyper Parallel Access Volumes to avoid the complicated performance design.
Cautions on using Compatible Super PAV
When Compatible Super PAV is enabled using Remote Web Console, the following cautions are required.
Operations in storage system
If the following operations are performed in the storage system, a host computer might not recognize all
alias volumes:
• Deleting alias volumes which are online.
• Turning off the power while JOB is running.
If alias volumes are not recognized, take the corrective actions to enable Compatible Super PAV. To make
sure that alias volumes are recognized, issue the following commands on the terminal of the host
computer:
ds qpav, bbbb(base volume), volume
The following is an output example of the status that alias volumes are recognized.
DS QP,EE66,VOL
IEE459I 21.57.57 DEVSERV QPAVS 789
HOST SUBSYSTEM
CONFIGURATION CONFIGURATION
--------------- ---------------------
UNIT UNIT UA
NUM. UA TYPE STATUS SSID ADDR. TYPE
----- -- ---- ------ ---- ---- ----------
0EE66 C6 BASE-H 7AF3 C6 BASE
1EE30 F0 ALIAS-H 7AF1 F0
1EE6F EF ALIAS-H 7AF3 EF
**** 3 DEVICE(S) MET THE SELECTION CRITERIA
16 Cautions on using Compatible Super PAV

The following is an output example of the status that alias volumes are not recognized. ALIAS-H does not
appear if alias volumes are not recognized.
DS QP,EE66,VOL
IEE459I 21.57.57 DEVSERV QPAVS 789
HOST SUBSYSTEM
CONFIGURATION CONFIGURATION
--------------- ---------------------
UNIT UNIT UA
NUM. UA TYPE STATUS SSID ADDR. TYPE
----- -- ---- ------ ---- ---- ----------
0EE66 C6 BASE-H 7AF3 C6 BASE
**** 1 DEVICE(S) MET THE SELECTION CRITERIA
If alias volumes are not recognized, execute the following commands on the terminal of the host
computer to re-recognize alias volumes.
vary bbbb-cccc (base volume), online, uncond
Alias volumes might not be re-recognized depending on the command execution timing, in which case
retry the operations. If alias volumes are not recognized yet, take the corrective actions listed in the
following table.
Operation Phenomenon Recommended action
Deleting alias volumes
which are online.
HPAV or Super PAV does
not work in the operated
storage system.
Take alias volumes offline from all connected
host computers.
Turning off the power while
JOB is running.
HPAV or Super PAV does
not work in the operated
storage system after turning
on the power.
Take alias volumes offline from all connected
host computers.
For details about the VARY command, see the descriptions about the VARY command in IBM "MVS
System Command".
Operations on host computer
When the PAV mode of the host computer is switched using the SETIOS command, the switchover
operation is asynchronously performed after completion of the SETIOS command. The amount of the
switchover processing time varies depending on the size or configuration of the connected system, the
load status imposed on the CPU, and others.
If the switchover operation of the PAV mode is not complete in any storage system, when the PAV mode
is switched to Super PAV again using the SETIOS command, the I/O operations of Super PAV might not
be performed in all storage systems connected to the host computer. To switch the PAV mode of the host
computer to Super PAV, perform the switchover operation at sufficient time intervals after the last PAV
mode switchover.
After switching over the PAV mode to Super PAV, make sure that alias volumes are recognized. If alias
volumes in different CUs do not appear, take the corrective action listed in the following table.
Operations on host computer 17

Operation Phenomenon Recommended action
Switching over the host
computer mode.
I/O operations of Super
PAV might not be
performed in all storage
systems connected to
LPAR even if the PAV mode
of the host computer is
switched to XPAV.
Take alias volumes offline from the host
computers on which alias volumes do not
appear.
(If alias volumes in different CUs do not
appear yet after coming online, take alias
volumes offline again.)
Restrictions on using Compatible Super PAV
The following table lists the restrictions on using Compatible Super PAV.
Restriction Recommended action
Compatible Super PAV cannot be used in
the system that has a CU in which both
devices with Data Exchange and devices
with mainframes are contained.
Both devices with Data Exchange and devices with
mainframes cannot be defined in one CU. If both devices
have been already defined as mixed, move either of the
devices to a different CU in order to change the
configuration so that there is no CU in which both devices
are contained. When Super PAV is enabled using Remote
Web Console, you cannot create a configuration where the
devices with Data Exchange and devices with mainframes
are contained in one CU.
Compatible Super PAV does not work in
CUs in which alias volumes are not
defined.
Make sure to define one or more alias volumes in CUs in
which you want to use Compatible Super PAV.
Alias volumes in CUs that do not contain
base volumes which are online cannot be
used by different CUs because they
cannot be recognized by a host computer.
In a CU in which you want to use alias volumes for
Compatible Super PAV, make the base volumes come
online to the host computer.
18 Restrictions on using Compatible Super PAV

Defining devices
Unused device addresses usage as alias devices
You can use unused device addresses in a CU as aliases for base devices. An optimum base-to-alias
device ratio ensures maximum efficiency in processing I/O requests.
Determining an optimum ratio depends on the type of PAV being used as well as the I/O rate for the
individual base devices. While some ratios are suggested, the best method is to use a tool that analyzes
your RMF data and recommends the appropriate number of aliases to configure for a base address. The
best tools will make recommendations for each type of PAV (static, dynamic, and HPAV).
Optimal Parallel Access Volumes results and base-to-alias device ratios
A ratio of 1:3 is recommended as a starting point for each base when using static PAV.
NOTE: The optimal device ratio will vary based on how often a base device is accessed by the host
system.
For example, if you define all 256 devices of a CU to the host system, 64 base devices and 192 alias
devices would exist. Three alias devices could be assigned to each base device.
Optimal dynamic PAV results and alias devices
Since dynamic PAV will change alias assignments, it is recommended that you start with a ratio of 1:1 for
a CU.
NOTE: If multiple host systems access devices, you can experience less than optimal results. In this
case, use Multiple Allegiance (MA) host software.
Hyper Parallel Access Volumes optimum base/alias device ratio
For HPAV, HPE recommends between 16 and 32 alias devices in a CU. These devices can be assigned
to a single base devices when performing configuration using Remote Web Console. All the aliases in a
CU will be placed in a pool and used as required for any base devices.
Compatible Super PAV optimum base/alias device ratio
As with HPAV, using 16 to 32 alias devices in a CU is also recommended for Super PAV.
The Super PAV feature uses alias devices in a CU where the base device belongs first as long as they
have enough space. Throughput performance improvement using Super PAV can be expected when the
number of used alias devices in a CU varies, and when CUs where few alias devices are used and CUs
where they run out are contained in an AMG. On the other hand, when alias devices are sufficient, effect
of using Super PAV might not be expected.
The methods for defining alias devices using Remote Web Console for HPAV and for Super PAV are the
same. Defined alias devices are grouped into an AMG containing even numbered CUs and into an AMG
containing odd numbered CUs. Base devices can use only alias devices in an AMG to which alias
devices in the local CU belongs. Therefore, balance the number of used alias devices across even
numbered CUs or odd numbered CUs.
Defining devices 19

Defining logical control units
You can use the HCD main screen to modify and view configuration data.
Prerequisites
• The channel paths are defined.
• You are using z/OS or z/VM.
Procedure
1. From the ISPF/PDF primary options menu, select the HCD option.
2. On the HCD main screen, for I/O definition file, for Work I/O definition file (IODF), verify the file is
the one you want to use and then select menu item 1, Define, modify, or view configuration data.
z/OS V1.11 HCD
Command ===> ________________________________________________________________
Hardware Configuration
Select one of the following.
1_ 0. Edit profile options
1. Define, modify, or view configuration data
2. Activate or process configuration data
3. Print or compare configuration data
4. Create or view graphical configuration report
5. Migrate configuration data
6. Maintain I/O definition files
7. Query supported hardware and installed UIMs
8. Getting started with this dialog
9. What's new in this release
For options 1 to 5, specify the name of the IODF to be used.
I/O definition file . . . 'SYS1.IODF00.WORK' +
3. On the Define, Modify or View Configuration Data screen, select menu item 1, Operating system
configurations.
z/OS V1.11 HCD
C Define, Modify, or View Configuration Data _
Select type of objects to define, modify, or view data.
S 4_ 1. Operating system configurations
consoles
1 system-defined generics
EDTs
esoterics
20 Defining logical control units