HP Scalable Visualization Array Software User Manual

HP Scalable Visualization Array Version 2.1
User's Guide

HP Part Number: A-SVAUG-4A
Published: March 2007

© Copyright 2006, 2007 Hewlett-Packard Development Company, L.P.

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Table of Contents

About This Document.......................................................................................................11

1 Intended Audience.............................................................................................................................11

2 Document Organization.....................................................................................................................11

3 Typographic Conventions..................................................................................................................11

4 Related Information...........................................................................................................................12

5 Publishing History.............................................................................................................................12

6 HP Encourages Your Comments........................................................................................................12

1 Introduction...................................................................................................................13

1.1 Where SVA Fits in the High Performance Computing Environment.............................................13

1.2 SVA Clusters....................................................................................................................................14

1.3 Displays...........................................................................................................................................15

1.4 SVA Functional Attributes...............................................................................................................15

1.4.1 Scalability................................................................................................................................15

1.4.2 Flexibility.................................................................................................................................16

1.5 Application Support........................................................................................................................16

1.5.1 OpenGL Applications.............................................................................................................17

1.5.2 Scenegraph Applications.........................................................................................................17

2 SVA Architecture...........................................................................................................19

2.1 SVA as a Cluster..............................................................................................................................19

2.1.1 Background on Linux Clusters................................................................................................19

2.2 Architectural Design.......................................................................................................................19

2.2.1 Components of the HP Cluster Platform................................................................................20

2.2.2 Main Visualization Cluster Tasks............................................................................................20

2.2.3 Components of an SVA...........................................................................................................21

2.2.4 Configuration Flexibility.........................................................................................................21

2.3 SVA Operation.................................................................................................................................22

2.3.1 Cluster Data Flow....................................................................................................................22

2.3.2 File Access...............................................................................................................................22

3 SVA Hardware and Software.....................................................................................25

3.1 Hardware Component Summary....................................................................................................25

3.2 Bounded Configuration...................................................................................................................26

3.3 Modular Packaging Configuration.................................................................................................27

3.4 Network Configurations.................................................................................................................27

3.4.1 System Interconnect (SI)..........................................................................................................27

3.4.2 Administrative Network Connections....................................................................................27

3.5 Display Devices...............................................................................................................................28

3.6 SVA Software Summary..................................................................................................................28

3.6.1 Linux Operating System..........................................................................................................29

3.6.2 HP XC Clustering Software.....................................................................................................29

3.6.3 Additional System Software....................................................................................................30

4 Quick Start....................................................................................................................33

4.1 Typical Uses of SVA.........................................................................................................................33

4.2 Configuring Displays for Use with SVA.........................................................................................33

4.3 Run a Test Application....................................................................................................................34

Table of Contents 3

4.3.1 Set Up Control for an Application..........................................................................................34

4.3.2 Launch an Application in Interactive Mode...........................................................................35

4.3.3 Launch an Application in Batch Mode....................................................................................36

4.3.4 Run an Application Using HP RGS.........................................................................................36

5 Setting Up and Running a Visualization Session......................................................39

5.1 Configuration Data Files.................................................................................................................39

5.2 Running an Application Using Scripts............................................................................................40

5.2.1 Selecting a Template or Script.................................................................................................40

5.2.2 Modifying a Script Template...................................................................................................41

5.2.3 Using a Script to Launch an Application................................................................................42

5.3 Running an Interactive Session.......................................................................................................42

5.4 Use Head or Remote-Capable Nodes in a Job.................................................................................43

5.4.1 Head Node..............................................................................................................................43

5.4.2 Remote-Capable Node............................................................................................................43

5.5 Using Nodes as a Different Type.....................................................................................................44

5.6 Running a Stereo Application.........................................................................................................44

5.7 G-Sync Framelock Support.............................................................................................................45

5.7.1 Use the Framelock Script Option............................................................................................45

5.7.2 Use the Framelock Script Function.........................................................................................46

5.7.3 Use the Framelock Utility........................................................................................................46

6 Application Examples..................................................................................................47

6.1 Running an Existing Application on a Single SVA Workstation....................................................47

6.1.1 Assumptions and Goal............................................................................................................47

6.1.2 HP Remote Graphics Software and Use..................................................................................48

6.1.2.1 Location for Application Execution and Control............................................................48

6.1.2.2 Data Access......................................................................................................................49

6.1.2.3 Use of Display Surfaces...................................................................................................49

6.1.2.4 Launch Script...................................................................................................................50

6.1.2.4.1 Non-Interactive Example........................................................................................50

6.1.2.4.2 Interactive Mode Example......................................................................................51

6.1.3 VirtualGL and TurboVNC Applications and Use...................................................................52

6.1.3.1 Assumptions....................................................................................................................52

6.1.3.2 Interactive Mode Example..............................................................................................53

6.1.3.3 Collaborative Viewing.....................................................................................................54

6.1.3.4 Encrypt the Connection with SSH..................................................................................54

6.1.3.4.1 Steps for Windows Desktops..................................................................................54

6.1.3.4.2 Steps for Linux Desktops........................................................................................55

6.2 Running Render and Display Applications Using ParaView.........................................................55

6.2.1 Assumptions and Goal............................................................................................................55

6.2.2 ParaView Overview.................................................................................................................56

6.2.3 Location for Application Execution and Control....................................................................56

6.2.4 Data Access..............................................................................................................................58

6.2.5 Use of Display Surfaces...........................................................................................................58

6.2.6 Launch Script Template ..........................................................................................................59

6.3 Running a Workstation Application Using a Multi-Tile Display...................................................59

6.3.1 Assumptions and Goal............................................................................................................59

6.3.2 Chromium Overview and Usage Notes..................................................................................59

6.3.3 Distributed Multi-Head X (DMX)...........................................................................................60

6.3.4 Location for Application Execution and Control....................................................................60

6.3.5 Data Access..............................................................................................................................61

6.3.6 Using Display Surfaces............................................................................................................62

4 Table of Contents

6.3.7 Launch Script...........................................................................................................................62

Glossary............................................................................................................................65

Index.................................................................................................................................67

Table of Contents 5

6

List of Figures

1-1 System View of a Computing Environment with Integrated SVA...............................................13

1-2 Standalone SVA Data Flow............................................................................................................14

1-3 Software Support for Application Development and Use............................................................16

2-1 SVA Data Flow Overview..............................................................................................................22

3-1 Sample SVA Bounded Configuration............................................................................................27

3-2 Software Hierarchy in the SVA......................................................................................................29

6-1 Using a Single SVA Node from Local Desktop.............................................................................49

6-2 ParaView Flow of Control on the SVA..........................................................................................57

6-3 Processes Running with Chromium-DMX Script.........................................................................61

7

8

List of Tables

3-1 Operating System and Driver Components..................................................................................29

3-2 HP XC System Components Relevant to SVA Operation.............................................................30

3-3 HP SVA System Software..............................................................................................................30

3-4 Third Party System Software.........................................................................................................31

3-5 Application Development Tools....................................................................................................31

6-1 Comparison Summary of Application Scenarios..........................................................................47

9

10

About This Document

The SVA User's Guide introduces the components of the HP Scalable Visualization Array (SVA).
The SVA product has hardware and software components that together make up the HP high
performance visualization cluster. This document provides a high level understanding of SVA
components.

The main purpose of the SVA is to give HP customers a platform on which to develop and run
graphics applications that require high performance combined with large data throughput on
single or multi-tile displays.

1 Intended Audience

The SVA User's Guide is intended for all users of the SVA. This includes visualization application
developers, visualization application users, system managers, and technical managers who need
a high level understanding of SVA.

2 Document Organization

This manual is organized into the following sections:

Chapter 1 Overview of SVA and where it fits in the HP Cluster Platform environment. It

also describes attributes of the SVA.

Chapter 2 Overview of SVA architecture, hardware, and software that make up the system.
Chapter 3 Additional detail on the hardware and software that make up the SVA.
Chapter 4 Summarizes how to get SVA sample applications running.
Chapter 5 Description of how to run a visualization application on the SVA.
Chapter 6 Description of common application examples as well as how to set them up on

the SVA.

3 Typographic Conventions

This document uses the following typographical conventions:

%, $, or #

audit(5) A manpage. The manpage name is audit, and it is located in

\ (backslash) Indicates the continuation of a command, where the line is too

Command
Computer output

Ctrl+x A key sequence. A sequence such as Ctrl+x indicates that you

ENVIRONMENT VARIABLE The name of an environment variable, for example, PATH.
[ERROR NAME]
Key The name of a keyboard key. Return and Enter both refer to the

Term The defined use of an important word or phrase.

User input

Variable

A percent sign represents the C shell system prompt. A dollar
sign represents the system prompt for the Bourne, Korn, and
POSIX shells. A number sign represents the superuser prompt.

Section 5.

long for the current page width.
A command name or qualified command phrase.
Text displayed by the computer.

must hold down the key labeled Ctrl while you press another
key or mouse button.

The name of an error, usually returned in the errno variable.

same key.

Commands and other text that you type.
The name of a placeholder in a command, function, or other

syntax display that you replace with an actual value.

1 Intended Audience 11

[] The contents are optional in syntax. If the contents are a list

{} The contents are required in syntax. If the contents are a list

... The preceding element can be repeated an arbitrary number of

 Indicates the continuation of a code example.
| Separates items in a list of choices.
WARNING A warning calls attention to important information that if not

CAUTION A caution calls attention to important information that if not

IMPORTANT This alert provides essential information to explain a concept or

NOTE A note contains additional information to emphasize or

4 Related Information

Related documentation is available via links from the home page for the SVA Documentation
Library on the HP XC Documentation CD. It also includes links to third party documentation
available on the Web that is relevant to users of SVA.

separated by a pipe ( | ), you must choose one of the items.

separated by a pipe ( | ), you must choose one of the items.

times.

understood or followed will result in personal injury or
nonrecoverable system problems.

understood or followed will result in data loss, data corruption,
or damage to hardware or software.

to complete a task

supplement important points of the main text.

5 Publishing History

The document printing date and part number indicate the document’s current edition. The
printing date will change when a new edition is printed. Minor changes may be made at reprint
without changing the printing date. The document part number will change when extensive
changes are made. Document updates may be issued between editions to correct errors or
document product changes. To ensure that you receive the updated or new editions, subscribe
to the appropriate product support service. See your HP sales representative for details. You can
find the latest version of this document on line at:

http://www.docs.hp.com.

Manufacturing Part
Number

A-SVAUG-4A

Systems

Software Version 3.2

6 HP Encourages Your Comments

HP encourages your comments concerning this document. We are committed to providing
documentation that meets your needs. Send any errors found, suggestions for improvement, or
compliments to:

[e-mail]

Include the document title, manufacturing part number, and any comment, error found, or
suggestion for improvement you have concerning this document.

Publication DateEdition NumberSupported VersionsSupported Operating

March, 20071Version 2.1HP XC System

12 About This Document

1 Introduction

Cluster System Interconnect

Compute Compute Compute Compute Compute

Visualization Visualization Visualization

HP SFS

Remote
PC

Display Surface

This chapter gives an overview of the HP Scalable Visualization Array (SVA). It describes how
the SVA works within the context of overall HP cluster solutions. It also discusses attributes of
the SVA that make it a powerful tool for running data intensive graphics applications.

The SVA is a scalable visualization solution that brings the power of parallel computing to bear
on many demanding visualization challenges.

The SVA leverages the advances made across the industry in workstation class systems, graphics
technology, processors, and networks by integrating the latest generations of these components
into its clustering architecture. This base of scalable hardware underlies powerful Linux clustering
software from HP. It is further enhanced by a set of utilities and support software developed by
HP and its partners to facilitate the use of the system by new and existing user applications.

1.1 Where SVA Fits in the High Performance Computing Environment

The SVA is an HP Cluster Platform system. It can be a specialized, standalone system consisting
entirely of visualization nodes, or it can be integrated into a larger HP Cluster Platform system
and share a single System Interconnect with the compute nodes and a storage system. Either
way, the SVA can integrate seamlessly into the complete computational, storage, and display
environment of customers as shown in Figure 1-1.

Figure 1-1 System View of a Computing Environment with Integrated SVA

High-speed networks make feasible the transfer of large amounts of data among the following:

• Individual users at their desktops, or logged into a cluster.

• The compute nodes, the visualization nodes, and local and remote display devices.

• Servers that are part of data storage farms.

A typical usage model for the type of system shown in Figure 1-1 has the following characteristics:

• A compute intensive application, for example, an automobile crash test simulation, runs on

the supercomputing compute nodes of the cluster.

• The large dataset generated on the compute nodes can be stored in the storage servers for

later retrieval, or directed in realtime for rendering on the SVA portion of the overall system.

• One or more users can log into the SVA concurrently, which allocates resources efficiently

to meet the rendering and display requirements of each user application.

• Users’ visualization applications use parallel programming techniques and visualization

middleware software to distribute their graphical rendering across the SVA nodes, each of
which in turn renders a portion of the output for the final image. Image data can be
apportioned by a master application to a set of visualization nodes for rendering.

• Each portion of the final image rendered by a visualization node is sent to a tile of a single

or multi-tile display. The complete image is available for display locally. The complete image

1.1 Where SVA Fits in the High Performance Computing Environment 13

is also available for display remotely, but limited to single or two-tile output from a single

OpenGL

Graphics

User Application

Master Node

user interface

transfer simulation data
and drawing commands

display nodes

System Interconnect

Card

OpenGL

Graphics

Card

OpenGL

Graphics

Card

OpenGL

Graphics

Card

multi-tile display

render nodes

OpenGL

Graphics

Card

OpenGL

Graphics

Card

OpenGL

Graphics

Card

graphics card.

The SVA serves as a key unit in an integrated computing environment that displays the results
of generated data in locations where scientists and engineers can most effectively carry out
analyses individually or collaboratively.

1.2 SVA Clusters

This section gives a high-level description of a standalone SVA, that is, an HP Cluster Platform
system built to include visualization nodes. The SVA can also provide a visualization solution
that is fully integrated into an existing HP Cluster Platform system with compute and storage
components, as shown in Figure 1-1.

The SVA image-based approach works with a variety of visualization techniques, including
isosurface extraction and volume visualization. Such a graphics architecture combines the high
performance of clustersof rendering machines with the interactivity made possible by the speed,
scalability, and low latency of the cluster network.

HP SVA offers a graphics visualization solution that can be used by a variety of applications that
run on distributed computing systems; in this case, a cluster of Linux workstations. Figure 1-2
illustrates the makeup of a standalone SVA.

Figure 1-2 Standalone SVA Data Flow

14 Introduction

Key points of Figure 1-2 are the following:

• Industry standard workstations and servers with standard OpenGL 3D graphics cardsserve
as visualization nodes (render and display), and run clustering software and Linux. Use of
industry standard graphics cards lets the system take advantage of new generations of cards
as they become available.

• Depending on the design of the application, an application “master” can run the application
and the user interface for the application on a specified node.

• Display nodes transfer their rendered output to the display devices and can synchronize
multi-tile displays. A range of displays are supported at locations local and remote to the
SVA. A series of render nodes can also contribute composited images to the display nodes,
depending on the visualization application. The HP Parallel Compositing Library that ships
with SVA can help application developers accomplish parallel rendering. See the SVA Parallel
Compositing Reference Guide.

• The System Interconnect (SI) supports data transfer among visualization nodes. High-speed,
low-latency networks such as InfiniBand and Myrinet can be used for the SI to speed the
transfer of image data and drawing commands to the visualization nodes.

Each portion of an image is rendered on its visualization node as determined by the application
and the visualization middleware being used. For example, you can use Chromium or a
scenegraph application in conjunction with Distributed MultiHead X (DMX). The final images
are transmitted by the graphics cards in the display nodes to the display devices.

Final images can also be transmitted to a remote workstation display over a network external to
the cluster. This lets users interact with applications running on the cluster from their offices.
Optionally, you can use HP Remote Graphics Software (RGS) or VirtualGL to accomplish this
more easily. See Chapter 6 for more information on both these packages.

Figure 1-2 also shows a master application node communicating with the other visualization

nodes over the SI. The SI carries file I/O and application communications; for example, MPI
traffic. The user interface for a visualization application can run on a master application node
and communicate with the visualization nodes over the SI, sending control information such as
changes in point of view, data, or OpenGL commands.

1.3 Displays

Display devices are not necessarily provided as part of the SVA. For example, your site can use
projector display systems or immersive displays provided by third party vendors.

Displays fall into a number of categories, including immersive CAVE displays, single monitors,
multiheaded monitors, large wall displays, multiheaded desktops, flat panels, and projector
displays used in theaters. SVA hardware and software deliver images to digital or analog standard
interfaces. The SVA depends on the graphics cards to drive the image output. This means the
wide range of display devices that the graphics cards support are available for use.

See Section 3.5 for more information.

1.4 SVA Functional Attributes

The key to SVA scalability and flexibility is its combination of cluster technology with high-speed
graphics cards and networks to transfer data. The SVA enables scaling up the number of nodes
working on a problem in parallel to handle larger dataset sizes, to increase frame rates, and to
display at higher image resolutions.

1.4.1 Scalability

There are a number of ways that applications can be designed and implemented to take advantage
of an SVA for effective scaling:

• Performance scaling: Render image data on separate nodes in the SVA. In effect, the work
is divided up among nodes working in parallel. Larger datasets can be accommodated by
more render nodes. The system design can scale from four to forty visualization nodes. This
count does not include the required head node.

The parallel attributes of the rendering pipeline removes a key performance bottleneck of
a conventional hardware accelerated graphics architecture, which feeds data sequentially
to a centralized pipeline.

In addition, the choice of a network that transmits data among the visualization nodes with
adequately low latency and high speed maintains interactive frame rates for delivery to the
display devices.

• Resolution scaling: Parallel rendering, combined with the parallel display of multiple tiles
makes such scaling possible. You can display high-resolution data and use large display
surfaces, including immersive displays and display walls.

In general, adding nodes to a dataset of fixed size provides good scaling up of the frame rate,
although speed-up is not linear because of the inevitable overhead due to portions of an
application's code that cannot be made parallel. However, a strength of SVA as a cluster
visualization platform is that scalability is nearly linear when the dataset size and node count
are both increased. For example, doubling the node count from four to eight makes it possible
to double the distributed dataset size with virtually no loss of frame rate. To achieve such gains
in frame rate, an application must be a true parallel application to efficiently distribute data and
to load balance across cluster nodes.

1.3 Displays 15

1.4.2 Flexibility

Visualization
Libraries
(optional)

Applications

X Servers

HP XC Linux

Allocate

Launch

Initialize

Cleanup

SVA
Software
Utilities

OpenGL

Cluster Nodes and Displays

One of the most powerful attributes of the SVA is its flexibility, which makes it possible to apply
the SVA effectively to a wide range of technical problems. This flexibility derives from the
architectural characteristics of the SVA.

When the architectural characteristics of the SVA are integrated with an HP high performance
compute cluster (see Figure 1-1), you can select an optimal number of application or compute
nodes and match them with an appropriate number of render and display nodes. Visual
applications with high computation requirements can be distributed over the compute nodes
and the visualization nodes; thus the render nodes can double as compute nodes.

This flexibility is critical because visualization applications often need to perform intensive
computations to compute isosurfaces, streamlines, or particle traces. You can select application
nodes based on factors such as model size, and match them to the visualization nodes your
application needs to yield the desired performance and resolution.

1.5 Application Support

This section introduces software support for application developers. Chapter 3 contains more
information on the software tools available for application developers.

HP recognizes that a key capability of the SVA is to make it possible for serial applications to
run without extensive recoding. To that end, HP works with both commercial ISVs and the open
source community to ensure solutions are available for the SVA.

Figure 1-3 illustrates the layers of software support and their hierarchical interrelationships that

are part of the SVA. These include:

• Cluster management software (HP XC) and visualization resource management software
(SVA Software Utilities).

• Visualization toolkits and libraries.

• User and third-party visualization applications.

Figure 1-3 also shows the tasks carried out by the SVA Software Utilities (part of the Visualization

System Software (VSS)). These tasks — allocate, launch, initialize, cleanup — are aligned alongside
the software layers they impact.

Figure 1-3 Software Support for Application Development and Use

Visualization and graphics toolkits are provided by third party vendors and the open source
community. ISV applications and applications written by end users can run on the SVA, taking

16 Introduction

full advantage of the various toolkits and libraries. The SVA uses standards such as OpenGL,
Linux, InfiniBand, and Gigabit Ethernet for portability and interoperability.

The HP Parallel Compositing Library that ships with SVA can help application developers
accomplish parallel rendering. See the SVA Parallel Compositing Reference Guide.

To achieve maximum performance scaling when running on the SVA, an application must be
parallel and distributed. There are two main pathways to this state: applications made parallel
by design and serial applications made parallel automatically through middleware libraries or
toolkits; for example, Chromium or other middleware.

1.5.1 OpenGL Applications

If your application is already parallel and distributed, you can use OpenGL directly.

Most visualization applications support OpenGL directly or through graphics toolkits.
Autoparallel toolkits such as Chromium, enable standard OpenGL applications to run on an
SVA with increased resolution, although without the performance advantages of a true parallel
application.

1.5.2 Scenegraph Applications

The SVA lets you take advantage of scenegraph applications available through scenegraph
middleware libraries and toolkits. The result is that the application is available on the SVA and
can take advantage of its parallel scalability features.

1.5 Application Support 17

18

2 SVA Architecture

This chapter gives a detailed look at the architecture of the HP Scalable Visualization Array
(SVA). It compares the SVA to other clusters and describes the flow of data within the cluster.

2.1 SVA as a Cluster

It is important to understand the cluster characteristics of the SVA. These characteristics have
implications for how SVA functions. They also affect how applications take advantage of cluster
features to achieve graphical performance and display goals.

2.1.1 Background on Linux Clusters

In the taxonomy of parallel computers, the SVA is most similar to a Beowulf class Linux cluster.
Beowulf clustershave many servers of the same type that communicate on high speed connections
such as channel bonded Ethernet. In this way, the cluster provides high performance for
applications capable of using parallel processing. This type of cluster can provide exceptional
computational performance.

A Beowulf cluster falls somewhere between the class of systems known as Massively Parallel
Processors (MPP) and a network of workstations (NOW). Examples of MPP systems include the
nCube, CM5, Convex SPP, Cray T3D, and Cray T3E. Beowulf clusters benefit from developments
in both these classes of architecture.

MPPs are typically larger and have a lower latency interconnect than a Beowulf cluster. However,
programmers on MPPs must take into account locality, load balancing, granularity, and
communication overheads to obtain the best performance. Even on shared memory machines,
many programmers develop programs that use message passing. Programs that do not require
fine-grain computation and communication can usually be ported and run effectively on a Linux
cluster.

Programming a NOW is usually an attempt to harvest unused cycles on an already-installed
base of workstations in a lab or on a campus. Programming in this environment requires
algorithms that are extremely tolerant of load balancing problems and large communication
latency. Any program that runs on a NOW runs at least as well on a cluster.

A Beowulf cluster is distinguished from a NOW by several subtle but significant characteristics.
These characteristics are shared by the SVA.

• Nodes in the cluster are dedicated to the cluster. This helps ease load balancing problems
because the performance of individual nodes is not subject to external factors.

• Because the System Interconnect (SI) is isolated from the external network, the network load
is determined only by the applications being run on the cluster. This eases problems
associated with unpredictable latency in NOWs.

• All nodes in the cluster are within the administrative jurisdiction of the cluster. For example,
the SI for the cluster is less visible to the outside world. Often, the only authentication needed
between processors is for system integrity. On a NOW, network security is an issue.

2.2 Architectural Design

The SVA derives its most powerful attributes from its architectural design, which consists of a
cluster of visualization nodes, high-speed interconnects, and advanced graphics cards.

SVA runs parallel visualization applications efficiently. The SVA also is an integral part of the
HP Cluster Platform and storage (HP Scalable File Share) solutions. To accomplish this, the SVA
architecture extends the HP Cluster Platform architecture with the addition of visualization
nodes, which you can use as specialized compute nodes. Further, an SVA can be made up entirely
of visualization nodes, or it can share an interconnect with compute nodes and a storage system.

2.1 SVA as a Cluster 19

Thus, the SVA provides the HP Cluster Platform with a visualization component for those
applications that require visualization in addition to computation.

The following sections describe the components that make up an HP Cluster Platform, followed
by those tasks and components that are unique to an SVA.

2.2.1 Components of the HP Cluster Platform

Because the SVA is an extension of the HP Cluster Platform, you can begin by understanding its
base components without any visualization nodes. The following are the key architectural
components of an HP Cluster Platform system without visualization nodes:

Compute Nodes and
Administrative/Service Nodes

System Interconnect (SI) A high-bandwidth, low-latency network which connects

Administrative Network An Administrative Network connects all nodes in the

Linux The nodes of the cluster run a derivative of 64-bit Red Hat®

The compute cluster consists of compute nodes and
administrative or service nodes. Parallel applications are
allocated exclusive use of the compute nodes on which
they run. The other nodes provide administration, software
installation, remote login, file I/O, external network access,
and so on. These nodes are shared by multiple jobs, and
are not allocated to individual jobs. One such node is
designated as the head node, which is used for
administration and connects to the external network.

all nodes. This supports communication among the
compute nodes (for example, MPI and sockets) and file
I/O between compute nodes and a shared file system.

cluster. In an HP XC compute cluster, this consists of two
branches, the Administrative Network and the Console
Network. This private local Ethernet network runs TCP/IP.
The Administrative Network is Gigabit Ethernet (GigE);
the Console Network is 10/100 BaseT. (Because
visualization nodes do not support console functions,
visualization nodes are not connected to a console branch.)

Enterprise Linux Advanced Server.

Note:

All nodes must attach to two networks using different ports, one for the SI and one for the
Administrative Network.

2.2.2 Main Visualization Cluster Tasks

The SVA has a number of tasks that are unique to a visualization-capable cluster. It accomplishes
these tasks using a set of unique node types that differ in their hardware configurations, and so
are capable of different functional tasks. The main tasks are as follows:

Render images. A node must have a graphics card to render images. A

Display images. The final output of a visualization application is a complete

20 SVA Architecture

visualization job uses multiple nodes to render image data
in parallel. A render node typically communicates over
the SI with other render and display nodes to composite
and display images.

displayed image that is the result of the parallel rendering
that takes place during an application job. To make this
possible, a display node must contain a graphics card
connected toa display device. The display can show images
integrated with the application user interface, or full screen

Remote images. The SVA also supports the transmission of a complete

Integrate an application user
interface.

2.2.3 Components of an SVA

The main tasks described in Section 2.2.2 are supported by two types of visualization nodes,
which differ in their configuration and in the tasks they carry out. The two nodes types can carry
out multiple tasks. These node types are unique to the SVA configuration and extend HP compute
clusters to support visualization functions. See Chapter 3 for detailed information on the hardware
configurations of these node types.

Display Nodes Display nodes carry out the display task. Typically, a displaynode contains

one or two graphics cards, each connected to its display device(s). The
output of each graphics card port (two ports per card) on a display node
can be sent to a display device. Final output can be a single tile or a partial
image in the form of a single tile, which is part of an aggregate multi-tile
display.

The SVA supports up to eight display nodes in a Display Surface. The
display nodes in your cluster can drive one or two display devices in the
case of the xw8200, xw8400, DL140 G3, and DL145 G3 nodes, and one to
four display devices in the case of xw9300 and xw9400 nodes. See the SVA
System Administration Guide for more information on setting up display
nodes, displays, and Display Surfaces.

images. The output can be a complete display or one tile
of an aggregate display.

image to a system external to the cluster over an external
network for remote viewing; for example, to an office
workstation outside the lab. A node with a port connected
to the external network is recommended. Alternatively,
you can connect to the external network by routing through
another cluster node with such a port.

An application user interface (UI) usually runs on a cluster
node. The UI typically controls the parts of the distributed
application running on other nodes. A node that provides
users with access to the UI can have an attached keyboard,
mouse, and monitor for user interaction. Alternatively, the
node can export the application UI to an external node
using the X protocol or using the HP Remote Graphics
Software (RGS) or VirtualGL. If you use RGS or VirtualGL,
a port connected to the external network is recommended.

Render Nodes Render nodes render images, as do display nodes. However, render nodes

are not connected directly to display devices. Typically, render nodes are
used by visualization applications that composite images. Render nodes
render a part of the final image. These sub-images are combined with
sub-images from other nodes. The composited image data is transferred
to another render node, or to a display node to be routed to a display device.

Render nodes are industry standard workstations or servers with standard
OpenGL 3D graphics cards.

Both types of nodes can perform UI and remote graphics functions. When nodes are allocated
to a job, the job typically requires specific display nodes that correspond to the display devices
intended for use. Typically, there is no requirement for specific render nodes.

2.2.4 Configuration Flexibility

The SVA supports several different configurations and uses. These include:

2.2 Architectural Design 21