User manual APPLE LEOPARD - XGRID ADMINISTRATION AND HIGH PERFORMANCE COMPUTING

Mac OS X Server Xgrid Administration and High Performance Computing For Version 10.5 Leopard Apple Inc. © 2007 Apple Inc. All rights reserved. The owner or authorized user of a valid copy of Mac OS X Server software may reproduce this publication for the purpose of learning to use such software. No part of this publication may be reproduced or transmitted for commercial purposes, such as selling copies of this publication or for providing paid-for support services. Every effort has been made to ensure that the information in this manual is accurate. Apple Inc. is not responsible for printing or clerical errors. Apple 1 Infinite Loop Cupertino, CA 95014-2084 408-996-1010 www.apple.com Use of the "keyboard" Apple logo (Option-Shift-K) for commercial purposes without the prior written consent of Apple may constitute trademark infringement and unfair competition in violation of federal and state laws. AirPort, Apple, the Apple logo, Bonjour, FireWire, iPod, Mac, Macintosh, Mac OS, Xgrid, Xsan, and Xserve are trademarks of Apple Inc., registered in the U.S. and other countries. Apple Remote Desktop and Finder are trademarks of Apple Inc. Intel, Intel Core, and Xeon are trademarks of Intel Corp. in the U.S. and other countries. Java and all Java-based trademarks and logos are trademarks or registered trademarks of Sun Microsystems, Inc. in the U.S. and other countries. UNIX is a registered trademark of The Open Group. Other company and product names mentioned herein are trademarks of their respective companies. Mention of third-party products is for informational purposes only and constitutes neither an endorsement nor a recommendation. Apple assumes no responsibility with regard to the performance or use of these products. 019-0946/2007-09-01 1 Contents Preface 9 9 9 10 10 11 12 12 13 13 About This Guide What's New in Xgrid Administration What's in This Guide Using This Guide Using Onscreen Help Advanced Server Administration Guides Viewing PDF Guides on Screen Printing PDF Guides Getting Documentation Updates Getting Additional Information Part I Chapter 1 17 17 18 20 20 21 21 22 23 23 24 24 24 25 25 26 26 27 Xgrid Administration Introducing Xgrid Service About Xgrid and Computational Grids How Xgrid Works Common Types of Grids and Grid Computing Styles Xgrid Clusters Local Grids Distributed Grids Xgrid Components Agent Client Controller Jobs Requirements and Capacities Setting Up and Configuring Xgrid Service Setup Overview Before Setting Up Xgrid Service Authentication Methods for Xgrid Single Sign-On (SSO) Chapter 2 3 27 27 28 28 28 29 29 30 30 30 31 32 33 34 34 34 35 35 36 37 37 37 38 Chapter 3 39 39 40 40 40 41 41 41 42 43 43 44 44 44 44 45 45 45 46 Password-Based Authentication No Authentication Hosting the Grid Controller Turning Xgrid Service On Configuring Xgrid with the Xgrid Service Configuration Assistant Configuring Xgrid to Host a Grid Using the Xgrid Service Configuration Assistant Configuring Xgrid to Join a Grid Using Xgrid Service Configuration Assistant Setting Up Xgrid Service Xgrid and Multiple Network Interfaces Configuring Controller Settings Starting Xgrid Service Configuring an Xgrid Agent (Mac OS X Server) Configuring an Xgrid Agent (Mac OS X) Setting Up Grid Authentication Setting Up Kerberos for Xgrid Setting Passwords for Xgrid Managing Client Access Setting SACL Permissions for Users and Groups Setting SACL Permissions for Administrators Managing Xgrid Service Viewing Xgrid Service Status Viewing Xgrid Service Logs Stopping Xgrid Service Managing a Grid Using Xgrid Admin Status Indicators in Xgrid Admin Managing the Xgrid Controller Connecting to an Xgrid Controller Disconnecting from an Xgrid Controller Adding an Xgrid Controller Removing an Xgrid Controller Managing Agents Viewing a List of Agents Adding an Agent Deleting an Agent Managing Jobs Viewing a List of Jobs Stopping a Job Repeating or Restarting a Job Deleting a Job Adding a Grid Deleting a Grid 4 Contents 46 Chapter 4 47 47 47 48 48 48 49 49 51 51 51 52 52 53 53 53 53 54 55 Monitoring Grid Activity Planning and Submitting Xgrid Jobs Structuring Jobs for Xgrid About Job Styles About Job Failure Submitting a Job Examples of Xgrid Job Submission and Results Retrieval Viewing Job Status Retrieving Job Results Solving Xgrid Problems If Your Agents Can't Connect to the Xgrid Controller If You Use Xgrid over SSH If You Run Tasks on Multi-CPU Machines If You Submit a Large Number of Jobs If You Want to Use Xgrid on Other Platforms If the Xgrid Controller Must Be Restarted If Xgrid Has Crashed If You Are Trying to Submit Jobs over 2 GB If You Want to Enable Kerberos/SSO for Xgrid For More Information Chapter 5 Part II Chapter 6 59 59 59 60 60 60 62 63 64 67 67 67 67 68 68 72 Configuring High Performance Computing Introducing High Performance Computing Understanding HPC Apple and HPC Mac OS X Server Xserve Clusters Xserve 64-Bit Architecture Support of Loosely Coupled Computations Reviewing the Cluster Setup Process Cluster Setup Overview Identifying Prerequisites and System Requirements Prerequisites Expertise Xserve Configuration System Requirements Infrastructure Requirements Software Requirements Chapter 7 Chapter 8 Contents 5 72 73 Chapter 9 75 75 78 81 81 84 85 86 86 87 88 90 90 90 91 92 93 94 95 95 98 98 99 101 101 102 103 103 104 105 106 107 111 111 112 112 Private Network Requirements Static IP Address and Hostname Requirements Preparing the Cluster for Configuration Preparing the Cluster Nodes for Software Configuration (Optional) Setting Up the Management Computer Setting Up the Cluster Controller Setting Up Server Software on the Cluster Controller Configuring DNS Service Verifying DNS Settings Configuring Open Directory Service Configuring the Cluster Controller as an Open Directory Master Configuring DHCP Service Configuring Firewall Settings on the Cluster Controller Configuring NAT Settings on the Cluster Controller Configuring NFS Configuring VPN Service Configuring Xgrid Service Preparing the Data Drive as a Mirrored RAID set Creating a Home Directory Automount Share Point Creating User Accounts Setting Up Compute Nodes Creating an Auto Server Setup Record for Compute Nodes Verifying LDAP Record Creation Setting Up Compute Nodes Configuring Cluster Nodes Creating and Verifying a VPN Connection Joining a Remote Client to the Kerberos Realm Verifying Remote Client Access to the Kerberos Realm Testing Your Cluster Checking Your Cluster Using Xgrid Admin Testing Your Xgrid Cluster Verifying Your Xgrid Configuration Verifying Your SSH Connection Cluster Setup Checklist Automating Compute Node Configuration Naming Multiple Cluster Nodes Joining Multiple Cluster Nodes to the Kerberos Realm Configuring Xgrid Agent Settings Using Apple Remote Desktop Chapter 10 Chapter 11 Chapter 12 Appendix A Appendix B 6 Contents 114 Glossary Index 115 121 Using SSH Without Passwords Contents 7 8 Contents This guide describes the Xgrid components included in Mac OS X Server and tells you how to configure and use them in computational grids. Xgrid in Mac OS X Server version 10.5 includes a controller for computational grids and an agent that allows the server's processor to work on jobs submitted to a grid. The agent is also available in computers using Mac OS X v10.3 or v10.4. What's New in Xgrid Administration Xgrid service, Xgrid Admin, and high performance computing (HPC) in Mac OS X Server v10.5 Leopard include the following valuable new features.  Improved security with Xgrid superuser access controls  New Xgrid service configuration assistant  Logging improvements What's in This Guide This guide is organized as follows:  Part I--Xgrid Administration. The chapters in this part of the guide introduce you to Xgrid service and the applications and tools available for administering xgrid.  Part II--Configuring High Performance Computing. The chapters in this part of the guide introduce you to HPC and the applications and tools available for administering HPC. Note: Because Apple frequently releases new versions and updates to its software, images shown in this book may be different from what you see on your screen. Preface 9 About This Guide Using This Guide The following list contains suggestions for using this guide:  Read the guide in its entirety. Subsequent sections might build on information and recommendations discussed in prior sections.  The instructions in this guide should always be tested in a nonoperational environment before deployment. This nonoperational environment should simulate, as much as possible, the environment where the computer will be deployed. Using Onscreen Help You can get task instructions on screen in Help Viewer while you're managing Leopard Server. You can view help on a server or an administrator computer. (An administrator computer is a Mac OS X computer with Leopard Server administration software installed on it.) To get help for an advanced configuration of Leopard Server: m Open Server Admin or Workgroup Manager and then:  Use the Help menu to search for a task you want to perform.  Choose Help > Server Admin or Help > Workgroup Manager to browse and search the help topics. The help for Server Admin and Workgroup Manager contains instructions taken from Server Administration and other advanced administration guides described in "Advanced Server Administration Guides," next. To see the latest server help topics: m Make sure the server or administrator computer is connected to the Internet while you're getting help. Help Viewer automatically retrieves and caches the latest server help topics from the Internet. When not connected to the Internet, Help Viewer displays cached help topics. 10 Preface About This Guide Advanced Server Administration Guides Getting Started covers basic installation and initial setup methods for a standard, workgroup, or advanced configuration of Leopard Server. An advanced guide, Server Administration, covers advanced planning, installation, setup, and more. A suite of additional guides, listed below, covers advanced planning, setup, and management of individual services. You can get these guides in PDF format from the Mac OS X Server documentation website at www.apple.com/server/documentation. This guide ... Getting Started and Mac OS X Server Worksheet Command-Line Administration File Services Administration iCal Service Administration iChat Service Administration Mac OS X Security Configuration Mac OS X Server Security Configuration Mail Service Administration Network Services Administration Open Directory Administration Podcast Producer Administration Print Service Administration QuickTime Streaming and Broadcasting Administration Server Administration tells you how to: Install Mac OS X Server and set it up for the first time. Install, set up, and manage Mac OS X Server using UNIX commandline tools and configuration files. Share selected server volumes or folders among server clients using the AFP, NFS, FTP, and SMB/CIFS protocols. Set up and manage iCal shared calendar service. Set up and manage iChat instant messaging service. Make Mac OS X computers (clients) more secure, as required by enterprise and government customers. Make Mac OS X Server and the computer it's installed on more secure, as required by enterprise and government customers. Set up and manage IMAP, POP, and SMTP mail services on the server. Set up, configure, and administer DHCP, DNS, VPN, NTP, IP firewall, NAT, and RADIUS services on the server. Set up and manage directory and authentication services, and configure clients to access directory services. Set up and manage Podcast Producer service to record, process, and distribute podcasts. Host shared printers and manage their associated queues and print jobs. Capture and encode QuickTime content. Set up and manage QuickTime streaming service to deliver media streams live or on demand. Perform advanced installation and setup of server software, and manage options that apply to multiple services or to the server as a whole. Use NetBoot, NetInstall, and Software Update to automate the management of operating system and other software used by client computers. Use data and service settings from an earlier version of Mac OS X Server or Windows NT. Create and manage user accounts, groups, and computers. Set up managed preferences for Mac OS X clients. System Imaging and Software Update Administration Upgrading and Migrating User Management Preface About This Guide 11 This guide ... Web Technologies Administration Xgrid Administration and High Performance Computing Mac OS X Server Glossary tells you how to: Set up and manage web technologies, including web, blog, webmail, wiki, MySQL, PHP, Ruby on Rails, and WebDAV. Set up and manage computational clusters of Xserve systems and Mac computers. Learn about terms used for server and storage products. Viewing PDF Guides on Screen While reading the PDF version of a guide on screen:  Show bookmarks to see the guide's outline, and click a bookmark to jump to the corresponding section.  Search for a word or phrase to see a list of places where it appears in the document. Click a listed place to see the page where it occurs.  Click a cross-reference to jump to the referenced section. Click a web link to visit the website in your browser. Printing PDF Guides If you want to print a guide:  Save ink or toner by not printing the cover page.  Save color ink on a color printer by looking in the panes of the Print dialog for an option to print in grays or black and white.  Maximize the printed page image by changing the Scale setting in the Page Setup dialog. Try 122% with Paper Size set to US Letter. (PDF pages are 7.5 by 9 inches except Getting Started, which is CD size, 125 by 125 mm.)  Reduce the bulk of the printed document and save paper by printing more than one page per sheet of paper. In the Print dialog, choose Layout from the untitled pop-up menu. If your printer supports two-sided (duplex) printing, select one of the TwoSided options. Otherwise, choose 2 from the Pages per Sheet pop-up menu, and optionally choose Single Hairline from the Border menu. 12 Preface About This Guide Getting Documentation Updates Periodically, Apple posts revised help pages and new editions of guides. Some revised help pages update the latest editions of the guides.  To view new onscreen help topics for a server application, make sure your server or administrator computer is connected to the Internet and click "Latest help topics" or "Staying current" in the main help page for the application.  To download the latest guides in PDF format, go to the Mac OS X Server documentation website: www.apple.com/server/documentation Getting Additional Information For more information, consult these resources:  Read Me documents--important updates and special information. Look for them on the server discs.  Mac OS X Server website (www.apple.com/macosx/server)--gateway to extensive product and technology information.  Apple Service & Support website (www.apple.com/support)--access to hundreds of articles from Apple's support organization.  Apple customer training (train.apple.com)--instructor-led and self-paced courses for honing your server administration skills.  Apple discussion groups (discussions.info.apple.com)--a way to share questions, knowledge, and advice with other administrators.  Apple mailing list directory (www.lists.apple.com)--subscribe to mailing lists so you can communicate with other administrators using email.  Open Source website (developer.apple.com/darwin/)--Access to Darwin open source code, developer information, and FAQs. Preface About This Guide 13 14 Preface About This Guide Part I: Xgrid Administration I Use the chapters in this part of the guide to learn about Xgrid service and the applications and tools available for administering Xgrid. Chapter 1 Chapter 2 Chapter 3 Chapter 4 Chapter 5 Introducing Xgrid Service Setting Up and Configuring Xgrid Service Managing a Grid Planning and Submitting Xgrid Jobs Solving Xgrid Problems 1 Introducing Xgrid Service 1 Use this chapter to learn about what Xgrid is and how it can help you. You use Xgrid to create grids of multiple computers and distribute complex jobs among them for high-throughput computing. Xgrid, a technology in Mac OS X Server and Mac OS X, simplifies deployment and management of computational grids. Xgrid enables administrators to group computers in grids or clusters, and enables users to easily submit complex computations to groups of computers (local, remote, or both), as either an ad hoc grid or a centrally managed cluster. About Xgrid and Computational Grids Xgrid makes it easy to turn an ad hoc group of Mac systems into a low-cost supercomputer. Xgrid is ideal for individual researchers, specialized collaborators, and application developers. For example:  Scientists can search biological databases on a cluster of Xserve systems.  Engineers can perform finite element analyses on their workgroup's desktops.  Animators can render images using Mac systems across multiple corporate locations.  Research teams can enlist colleagues and interested laypeople in Internet-scale volunteer grids to perform long-running scientific calculations.  Anyone needing to perform CPU-intensive calculations can simultaneously run a single job across multiple computers, dramatically improving throughput and responsiveness. With Xgrid functionality integrated into Mac OS X Server, system administrators can quickly enable Xgrid on Mac systems throughout their company, turning idle CPU cycles into a productive cluster at no incremental cost. 17 How Xgrid Works Xgrid creates multiple tasks for each job and distributes those tasks among multiple nodes. These nodes can be desktop computers running Mac OS X v10.3 or later, or server computers running Mac OS X Server v10.4 or later. Many desktop computers sit idle during the day, in evenings, and on weekends. The assembly of these systems into a computational grid is known as desktop recovery. This method of grid construction enables you to vastly improve your computational capacity without purchasing extra hardware, and Xgrid makes the software configuration a straightforward task. For a server to function as a controller, Xgrid requires Mac OS X Server v10.4 or later, with a minimum of 256 MB of RAM. To operate as an agent in a grid, Xgrid requires Mac OS X v10.3 or later, with a minimum of 128 MB of RAM (256 MB advisable). All Xgrid participants must have a network connection. As always, the more RAM a system has, the better it performs, particularly for high-performance computing applications. A grid is a group of computers working together to solve a single problem. The systems in a grid can be loosely coupled, geographically dispersed and, to some extent, heterogeneous. In contrast, systems in a cluster are often homogeneous, collocated, and strictly managed. Highly dispersed grids, such as SETI@Home, enable individuals to donate their spare processor cycles to a cause. In office environments, large rendering or simulation jobs can be distributed across all the systems left idle overnight. These can even be used to augment a dedicated computational cluster, which is available to Xgrid clients at all times. These distinct grid configurations are explained in "Common Types of Grids and Grid Computing Styles" on page 20. 18 Chapter 1 Introducing Xgrid Service The illustration below gives an example of how a grid handles a job. Distributed agents 1 Client submits job to Controller 2 Controller splits job into tasks, then submits tasks to Agents 3 Agents execute tasks Dedicated Desktop Controller Client Dedicated Server 5 Controller collects tasks and returns job results to Client 4 Agents return tasks to Controller Part-Time Desktop Xgrid has no limitations on the amount of computational power it can support. The performance of the grid depend on the systems participating, the software running, and the network, among other factors. However, individual applications strongly influence the performance of the grid. You determine if an application is improved by being deployed on a computational grid. In the best case, application performance may scale linearly with the size of the grid. In the worst case, the addition of agents to a grid can cause a job to complete in even more time than if there were fewer agents. (In such a situation, tasks become so small that the overhead associated with distributing the increased number of tasks supersedes the performance gain of using more agents.) You should be aware of these considerations. Many proprietary projects enable you to participate in a large computational grid. Often these projects, such as SETI@Home and FightAIDS@Home, are tied to a specific scientific purpose. They usually have easy-to-install software that enables any volunteer to participate in that particular project, and they frequently take the form of a screen saver or background process. Chapter 1 Introducing Xgrid Service 19 You don't need to think in terms of thousands or millions of seldom-used computers to see the significance of a computational grid. For example, computers used by university students or corporate employees often work fewer hours than the hours they sit idle at night or on weekends. These computers could contribute productively to the work of a grid without diminishing their usefulness to the students or employees. Other grid projects are designed for large-scale computational grids, such as the Globus Alliance (a group founded by universities and researchers), with flexible resource management tools and more intelligent grid deployment methods. Instead of developing neatly packaged applications for a specific grid, such projects provide comprehensive frameworks for application deployment. Xgrid enables users to participate in a computational grid of their choice while still providing the flexibility of a more generic framework for grid developers when deploying grid applications. Xgrid provides the primary benefits of both. The advantages of the Xgrid technology include:  Easy grid configuration and deployment  Straightforward yet flexible job submission  Automatic controller discovery by agents and clients  Flexible architecture based on open standards  Support for the UNIX security model, including Kerberos single sign-on or regular password authentication  Choice between a command-line interface or an API-based model for grid interaction Common Types of Grids and Grid Computing Styles Xgrid can be used in tightly coupled clusters, worldwide grids, and everything in between. This immense flexibility enables you to deploy grids of almost any nature. Three main topologies are commonly used for Xgrid deployments, discussed as follows:  "Xgrid Clusters" on page 20  "Local Grids" on page 21  "Distributed Grids" on page 21 Xgrid Clusters Computational clusters are sets of systems dedicated to computation. In a cluster, systems are typically co-located in a rack, connected using gigabit Ethernet or another high-performance network, and strictly managed for maximum performance. Cluster systems are often entirely homogeneous: their operating systems are the same versions, they have the same software installed, and they generally have the same processor, disk, and RAM configurations. 20 Chapter 1 Introducing Xgrid Service Xgrid enables administrators to easily configure the distributed resource management functionality of the cluster. Each server in the system runs the agent software, and the head node in the cluster runs the controller software. Xgrid distributes tasks across the cluster. In clusters, failure rates are generally very low. Systems are rarely, if ever, offline, and their resources are not shared with general user tasks. Clusters are the most efficient but most expensive model of distributed computing. Local Grids Systems that are under common administration in a company, university computer lab, or other managed environment can often be easily assembled into a grid for desktop recovery. These systems are often on a local area network (LAN) and they are generally managed by a single organization. As a result, they provide good network performance and offer substantial manageability. Because these systems are often also used as day-to-day workstations, users can easily interrupt grid tasks by moving the mouse, resetting the system, or even accidentally disconnecting the system from the network. In such cases, a task might fail as part of an Xgrid job the Xgrid controller eventually reassigns the failed task to another agent, and the job completes successfully. In local grids, performance is limited by such situations and by the varying performance of any given agent on the grid. Distributed Grids When a system is permitted to donate its time, a distributed grid is formed. The Xgrid agent enables a user to specify any IP address or host name for its controller. By specifying a grid, a user can dedicate his or her CPU time to that grid no matter where the controller is located. The manager of the controller has no direct management control or knowledge of the agent system but is nonetheless able to harness its CPU time. Distributed grids have very high failure rates for jobs but place a very low burden for the grid administrator. With very, very large jobs, high task failure rates may not substantially affect the performance of the grid if such failures can be rapidly reassigned to other available agents. Network performance can also be a consideration because data is sent over the Internet, rather than over a local network, to agents connected to a grid. The monetary cost of such distributed grids is extremely low. Chapter 1 Introducing Xgrid Service 21 Xgrid Components The Xgrid three-tier architecture simplifies the distribution of complicated tasks. Its user clients, grid controllers, and computational agents work together to streamline the process of assembling nodes, submitting jobs, and retrieving results. The illustration below gives an example of the Xgrid components and the process of auto configuration for a grid. Distributed agents 4 Client submits using mDNS, DNS, or name/address 2 Agents locate Controller using mDNS, DNS, or name/address 1 Controller advertises via mDNS Controller Client 5 Clients and Controller mutually authenticate using passwords or single sign-on 3 Agents and Controller mutually authenticate using passwords or single sign-on Dedicated Desktop Dedicated Server Part-time Desktop The primary components of a computational grid perform the following functions:  An agent runs one task at a time per CPU; a dual-processor computer can run two tasks simultaneously.  A controller queues tasks, distributes those tasks to agents, and handles task reassignment.  A client submits jobs to the Xgrid controller in the form of multiple tasks. (A client can be any computer running Mac OS X v10.4 or later or Mac OS X Server v10.4 or later.) In principle, the agent, controller, and client can run on the same server, but it is often more efficient to have a dedicated controller node. 22 Chapter 1 Introducing Xgrid Service Agent Xgrid agents run the computational tasks of a job. In Mac OS X Server, the agent is turned off by default. When an agent is turned on and becomes active at startup, it registers with a controller. (An agent can be connected to only one controller at a time.) The controller sends instructions and data to the agent as needed for the controller's jobs. After it receives instructions from the controller, the agent performs its assigned tasks and sends the results back to the controller. By default, agents seek to bind to the first available controller on the LAN. Alternatively, you can specify that it bind to a specific controller. You can also specify whether an agent is always available or is available only when the computer is idle. A computer is considered idle when it has no mouse or keyboard input and ignores CPU and network activity. If a user returns to a computer that is running a grid task, the computer continues to run the task until it is finished. By default, the agent on Mac OS X Server is dedicated and the agent on a Mac OS X computer (not a server) is configured to accept tasks only when the computer has had no user input for 15 minutes. For details about configuring an agent, see "Configuring an Xgrid Agent (Mac OS X Server)" on page 32. For information about managing agents, see "Managing Agents" on page 42. Client Any system can be an Xgrid client if it is running Mac OS X v10.4 or later and has a network connection to the Xgrid controller system. In general, the client can connect to only a single controller. Depending on how a controller is configured, the client must supply a password or be authenticated by Kerberos (single sign-on) before submitting a job to the grid. A user submits a job to the controller from a system running the Xgrid client software, usually a command-line tool accessed with the Terminal application. The job can specify the controller or use multicast DNS (mDNS) to dynamically discover the first available controller. When the job is complete, the controller notifies the client and the client can retrieve the results of the job. For information about client authentication to the controller, see "Setting Up Grid Authentication" on page 34. Chapter 1 Introducing Xgrid Service 23 Controller The Xgrid controller manages the communications among the computational resources of a grid. The controller requires Mac OS X Server v10.4 or later. The controller accepts network connections from clients and agents. It receives job submissions from clients, divides the jobs into tasks, dispatches tasks to agents, and returns results to the clients. Although there can be more than one Xgrid controller running on a subnet, there can only be one controller per logical grid. Each controller can have an arbitrary number of agents connected, but Apple has tested 128 agents per controller. However, there is no software limitation on the number of agents, and users of Xgrid can choose to exceed 128 agents on a controller at their own risk, with a theoretical maximum equal to the number of available sockets on the controller system. For details about setting up an Xgrid controller, see "Configuring Controller Settings" on page 30. For information about managing controllers and grids, see "Managing the Xgrid Controller" on page 40. Jobs A job is a collection of execution instructions that can include data and executables. Xgrid can run scripts, utilities, and custom software (anything that doesn't require user interaction). A client submits a job to the grid. The controller accepts the job and its associated files, divides the job into tasks, and then distributes the tasks to agents. Agents accept the tasks, perform the calculations, and return the results to the controller, which aggregates them and returns them to the clients. For more information about jobs, see "Structuring Jobs for Xgrid" on page 47 and "Submitting a Job" on page 48. Requirements and Capacities Xgrid is designed to scale from small clusters of a few computers up to large organization-wide grids. Xgrid supports up to 128 agents, any number of jobs comprising up to 100,000 queued tasks, up to 128 MB of submitted data per job, and up to 128 MB of results per job. These are recommended limits and are not enforced by the software. You may choose to exceed these limits at your own risk. 24 Chapter 1 Introducing Xgrid Service 2 Setting Up and Configuring Xgrid Service 2 Use this chapter to plan your grid and set up the Xgrid agent and controller. Xgrid simplifies deployment and management of computational grids. Using Server Admin you can configure Xgrid to set up computer groups (grids or clusters) and allow users to easily submit complex computations to these grids (local, remote, or both), as either an ad hoc grid or a centrally managed cluster. Setup Overview Here is an overview of the steps for setting up Xgrid service: Step 1: Before you begin See "Before Setting Up Xgrid Service" on page 26. Identify the Xgrid environment you need. Before configuring Xgrid, you must make some decisions about the grid. Step 2: Turn Xgrid service on Prior to configuring, turn on Xgrid service. See "Turning Xgrid Service On" on page 28. Step 3: (Optional) Use the Xgrid service configuration assistant to configure Xgrid If you choose to, you can configure Xgrid using the Xgrid service configuration assistant. This assistant helps with Xgrid configuration by automating many of the settings you make. See "Configuring Xgrid with the Xgrid Service Configuration Assistant" on page 28. Step 4: Configure Xgrid controller settings Configure your server as an Xgrid controller using Server Admin. See "Configuring Controller Settings" on page 30. Step 5: Start Xgrid service Start Xgrid service on the server using Server Admin. See "Starting Xgrid Service" on page 31. 25 Step 6: Configure Xgrid agent settings (Mac OS X Server) Configure your server as an Xgrid agent using Server Admin. See "Configuring an Xgrid Agent (Mac OS X Server)" on page 32. Step 7: Configuring Xgrid agent settings (Mac OS X) Configure computers as Xgrid agents by using Sharing Preferences. See "Configuring an Xgrid Agent (Mac OS X)" on page 33. Before Setting Up Xgrid Service Before configuring Xgrid service, you must define the grid environment you'll create. In particular, you must decide the following:  The kind of authentication to use. See "Authentication Methods for Xgrid" on page 26.  Where to host your controller. See "Hosting the Grid Controller" on page 28.  How you will manage the controller. See "Managing Xgrid Service" on page 37 and "Monitoring Grid Activity" on page 46. Authentication Methods for Xgrid You can configure Xgrid with or without authentication. If you choose to require authentication of controllers to mutually authenticate with clients and agents, you can choose Single Sign-On or Password-Based Authentication. The following authentication options are available:  Single Sign-On  Password-Based Authentication  No Authentication You set up an Xgrid controller using Server Admin. You can specify the type of authentication for agents and clients. The passwords entered in Server Admin for the controller must match those entered for each agent and client. Consider these points when establishing passwords for agents and clients:  Kerberos authentication (single sign-on or SSO). If you use Kerberos authentication for agents or clients, the server that's the Xgrid controller must be configured for Kerberos, in the same realm as the server running the Kerberos domain controller (KDC) system, and bound to the Open Directory master. The agent uses the host principal found in the /etc/krb5.keytab file. The controller uses the Xgrid service principal found in the /etc/krb5.keytab file.  Agents. The agent determines the authentication method. The controller must conform to that method and password (if a password is used). When an agent is configured with a standard password (not SSO), you must use the same password for agents when you configure the controller. If the agent has specified SSO, the correct service principal and host principals must be available. 26 Chapter 2 Setting Up and Configuring Xgrid Service  Clients. If your server is the controller for a grid, be sure that Mac OS X and Mac OS X Server clients use the correct authentication method for the controller. A client cannot submit a job to the controller unless the user chooses the correct authentication method and enters their password correctly, or has the correct ticketgranting ticket from Kerberos. For more information, see "Setting Up Grid Authentication" on page 34. Single Sign-On (SSO) SSO is the most powerful and flexible form of authentication. It leverages the Open Directory and Kerberos infrastructures in Mac OS X Server to manage authentication behind the scenes, without user intervention. Each Xgrid participant must have a Kerberos principal. The clients and agents obtain ticket-granting tickets for their principal, which is used to obtain a service ticket for the controller service principal. The controller looks at the ticket granted to the client to determine the user's principal and verifies it with the relevant service access control lists (SACLs) and groups to determine privileges. Generally, you should use this option if any of the following conditions are true:  You already have SSO in your environment.  You have administrator control over all agents and clients in use.  Jobs must run with special privileges (such as for local, network, or SAN file system access). Password-Based Authentication When you can't use SSO, you can require password authentication. You may not be able to use SSO if:  Potential Xgrid clients are not trusted by your SSO domain (or you don't have one)  You want to use agents across the Internet or that are outside your control  It is an ad hoc grid, without the ability to prearrange a web of trust In these situations, your best option is to specify a password. You have two distinct password settings: one for controller-client and one for controller-agent. For security reasons these should be different passwords. Note: You can also create hybrid environments, such as with client-controller authentication done using passwords but controller-agent authentication done using SSO (or vice versa). No Authentication This option is suitable only for testing a private network in a home or a lab that is inaccessible from any untrusted computer, or when none of the jobs or the computers contain sensitive or important information. Chapter 2 Setting Up and Configuring Xgrid Service 27 Otherwise, do not use this option. It creates a potential security hole (because anyone can connect or run a job) and should never be used on a system exposed to the Internet, especially when potentially sensitive data is involved. If you choose to use no authentication, agents can join the grid and clients can submit jobs to the grid without authenticating. Hosting the Grid Controller The primary requirement for a controller is that it must be network-accessible to clients and agents. In some cases this may mean the controller must be placed outside an organizational firewall (or inside a buffer zone); otherwise, you would need to open up port 4111 so the controller can be contacted. It is much simpler (though not essential) for the controller to be on the same subnet as the agents and usual clients, so they can discover each other using Bonjour. If that's not feasible, host the controller on a server with a fixed IP address and fully qualified DNS name (or alternatively, using Dynamic DNS and a service lookup entry) so that agents and clients know where to find it. Turning Xgrid Service On Before you can configure Xgrid settings, you must turn Xgrid service on in Server Admin. To turn Xgrid service on: 1 Open Server Admin and connect to the server. 2 Click Settings. 3 Click Services. 4 Select the Xgrid checkbox. 5 Click Save. Configuring Xgrid with the Xgrid Service Configuration Assistant You can set up Xgrid service by configuring the controller and agent using the Xgrid service configuration assistant. This optional configuration assistant guides you through setting up a server to host a grid or join an existing grid. Before this assistant proceeds, your server must have access to a directory server that provides Kerberos services. 28 Chapter 2 Setting Up and Configuring Xgrid Service Configuring Xgrid to Host a Grid Using the Xgrid Service Configuration Assistant Use the Xgrid service configuration assistant to configure the Xgrid agent and controller to run on this server. This also configures a network file system. To set up Xgrid to host a grid using the Xgrid service configuration assistant: 1 Open Server Admin and connect to the server. 2 Click the triangle to the left of the server. The list of services appears. 3 In the expanded Servers list, click Xgrid. 4 Click Overview. 5 Click Configure Xgrid Service (at the lower right). This opens the Xgrid service configuration assistant. 6 Click Continue. 7 Choose "Host a grid," then click Continue. 8 Enter the username and password for the directory administrator to authenticate with the directory domain displayed, then click Continue. 9 Review and confirm your configuration settings, then click Continue. This restarts Xgrid service using your settings. 10 Click Close. Configuring Xgrid to Join a Grid Using Xgrid Service Configuration Assistant Use the Xgrid service configuration assistant to configure the Xgrid agent to run on this server. Joining a grid means that an agent is set up on this server and is bound to an existing controller. To join a grid using the Xgrid service configuration assistant: 1 Open Server Admin and connect to the server. 2 Click the triangle to the left of the server. The list of services appears. 3 In the expanded Servers list, click Xgrid. 4 Click Overview. 5 Click Configure Xgrid Service (at the lower right). This opens the Xgrid service configuration assistant. 6 Click Continue. 7 Choose "Join a grid," then click Continue. Chapter 2 Setting Up and Configuring Xgrid Service 29 8 Specify the controller you want to bind your agent to. Select "Browse Bonjour-discoverable controllers" to view and select from available controllers. Select "Use controller with hostname" to enter the hostname of a specific controller. 9 Click Continue. 10 Review and confirm your configuration settings, then click Continue. This restarts Xgrid service using your settings. 11 Click Close. Setting Up Xgrid Service You set up Xgrid service by configuring two groups of settings on the Settings pane for Xgrid service in Server Admin:  Controller. Use to configure your server as an Xgrid controller and set client and agent authentication.  Agent. Use to configure your server as an Xgrid agent, to specify the controller, and to set controller authentication. The following section describes how to configure these settings. An additional section tells you how to start Xgrid service when you finish. (By default, the Xgrid controller and agent are disabled.) Important: If you specify a password, the agent and controller must use the same password or must authenticate using Kerberos (SSO). For information about authentication options, see "Setting Passwords for Xgrid" on page 34. Xgrid and Multiple Network Interfaces On a server with multiple network interfaces, Mac OS X Server makes Xgrid service available over all interfaces. You can't configure Xgrid service separately for each interface. Configuring Controller Settings You use Server Admin to configure an Xgrid controller. When configuring the controller, you can also set a password for any agent using the grid and for any client that submits a job to the grid. To configure an Xgrid controller: 1 Open Server Admin and connect to the server. 2 Click the triangle to the left of the server. The list of services appears. 3 In the expanded Servers list, click Xgrid. 30 Chapter 2 Setting Up and Configuring Xgrid Service 4 Click Settings. 5 Click Controller. 6 Click "Enable controller service." 7 From the Client Authentication pop-up menu, choose one of the following authentication options for clients and enter the password.  Password requires that the agent and controller use the same password.  Kerberos uses SSO authentication for the agent's administrator.  None does not require a password for the agent. This option provides no protection from potentially malicious use of your grid. With no authentication, a malicious agent could receive tasks and potentially access sensitive data. For details about password options, see "Setting Up Grid Authentication" on page 34. 8 From the Agent Authentication pop-up menu, choose from the following authentication options for agents and enter the password. Password requires that the agent and controller use the same password. Kerberos uses SSO authentication for the agent's administrator. Any uses any authentication available for the agent's administrator. None does not require a password for the agent. This option provides no protection from potentially malicious use of your grid. With no authentication, a malicious agent could receive tasks and potentially access sensitive data. For information about password options, see "Setting Up Grid Authentication" on page 34. 9 Click Save. Important: If you require authentication, the agent and controller must use the same password or must authenticate using Kerberos (SSO). For information about authentication options, see "Setting Up Grid Authentication" on page 34.     Starting Xgrid Service Use Server Admin to start Xgrid service. The Xgrid service must be running for your server to control a grid or participate in a grid as an agent. For details about using the server as an agent and controller, see "Configuring an Xgrid Agent (Mac OS X Server)" on page 32 and "Configuring Controller Settings" on page 30. After you start Xgrid, it restarts when the server is restarted. To start Xgrid service: 1 Open Server Admin and connect to the server. Chapter 2 Setting Up and Configuring Xgrid Service 31 2 Click the triangle to the left of the server. The list of services appears. 3 In the expanded Servers list, click Xgrid. 4 Click the Start Xgrid button (below the Servers list). Configuring an Xgrid Agent (Mac OS X Server) You use Server Admin to set up your server as an Xgrid agent. In addition, you can associate the agent with a specific controller or permit it to join a grid, specify when the agent accepts tasks, and set a password that the controller must recognize. To configure an Xgrid agent on the server: 1 Open Server Admin and connect to the server. 2 Click the triangle to the left of the server. The list of services appears. 3 In the expanded Servers list, click Xgrid. 4 Click Settings. 5 Click Agent. 6 Click "Enable agent service." 7 Specify a controller by choosing its name in the Controller pop-up menu or by entering the controller name. By default, the agent uses the first available controller. Note: An agent can find a controller in one of three ways: a specific hostname or IP address, the first available controller that advertises on Bonjour on the local subnet, or to a specific Bonjour service name. 8 Specify when the agent will accept tasks. Tasks can be accepted when the computer is idle or always. A computer is considered idle when it has no mouse or keyboard input and ignores CPU and network activity. If a user returns to a computer that is running a grid task, the computer continues to run the task until it is finished. 9 From the pop-up menu, choose one of the following authentication options and enter the password. For details, see "Setting Up Grid Authentication" on page 34.  Password requires that the agent and controller use the same password.  Kerberos uses SSO authentication for the agent's administrator.  None does not require a password for the agent. This option provides no protection from potentially malicious use of your grid. With no authentication, a malicious agent could receive tasks and potentially access sensitive data. 32 Chapter 2 Setting Up and Configuring Xgrid Service 10 Click Save. Important: If you require authentication, the agent and controller must use the same password or must authenticate using Kerberos SSO. For details about authentication option, see "Setting Up Grid Authentication" on page 34. Configuring an Xgrid Agent (Mac OS X) You use Sharing preferences to set up client computers as Xgrid agents. In addition, you can associate the agent with a specific controller or permit it to join any grid, specify when the agent accepts tasks, and set a password that the controller must recognize. To configure an Xgrid agent on a client: 1 On the client computer, open Sharing preferences and click Services. 2 Click Xgrid and then click Configure. 3 Specify a controller by choosing its name in the Controller pop-up menu or by entering the controller name. By default, the agent uses the first available controller. Note: An agent can find a controller in one of three ways: a specific hostname or IP address, the first available controller that advertises on Bonjour on the local subnet, or to a specific Bonjour service name. 4 Specify when the agent will accept tasks. Tasks can be accepted when the computer is idle or always. A computer is considered idle when it has no mouse or keyboard input and ignores CPU and network activity. If a user returns to a computer that is running a grid task, the computer continues to run the task until it is finished. 5 Choose one of the following authentication options from the pop-up menu and enter the password. For more information, see "Setting Up Grid Authentication" on page 34.  Password requires that the agent and controller use the same password.  Kerberos uses SSO authentication for the agent's administrator.  None does not require a password for the agent. This option provides no protection from potentially malicious use of your grid. With no authentication, a malicious agent could receive tasks and potentially access sensitive data. 6 Click OK. Important: If you require authentication, the agent and controller must use the same password or must authenticate using Kerberos (SSO). For more information about authentication options, see "Setting Up Grid Authentication" on page 34. 7 Click Start to turn Xgrid sharing on. Chapter 2 Setting Up and Configuring Xgrid Service 33 Setting Up Grid Authentication You can configure Xgrid to require authentication of controllers, clients, and agents. For more information, see "Authentication Methods for Xgrid" on page 26. Setting Up Kerberos for Xgrid You use Server Admin to configure Kerberos as the authentication method for your Xgrid. Kerberos authentication uses SSO. To configure Kerberos authentication: 1 Open Server Admin and connect to the server. 2 Click the triangle to the left of the server. The list of services appears. 3 In the expanded Servers list, click Xgrid. 4 Click Settings. 5 Click Agent. 6 Click "Enable agent service." 7 For the authentication option for the agent, choose Kerberos from the Controller Authentication pop-up menu. 8 Click Controller. 9 Click "Enable controller service." 10 For the authentication option for the client, choose Kerberos from the Client Authentication pop-up menu. 11 For the authentication option for the agent, choose Kerberos from the Agent Authentication pop-up menu. 12 Click Save and restart the service. Setting Passwords for Xgrid You use Server Admin to configure your Xgrid controllers to authenticate clients and agents using password authentication. Password authentication requires that the agent and controller use the same password. You specify password options in Server Admin as part of configuring the agent and controller. See "Configuring an Xgrid Agent (Mac OS X Server)" on page 32 and "Configuring Controller Settings" on page 30. To configure password authentication: 1 Open Server Admin and connect to the server. 2 Click the triangle to the left of the server. The list of services appears. 34 Chapter 2 Setting Up and Configuring Xgrid Service 3 In the expanded Servers list, click Xgrid. 4 Click Settings. 5 Click Agent. 6 Click "Enable agent service." 7 For the authentication option for the agent, choose Password from the Controller Authentication pop-up menu and enter a password. 8 Click Controller. 9 Click "Enable controller service." 10 For the authentication option for the client, choose Password from the Client Authentication pop-up menu and enter a password. 11 For the authentication option for the agent, choose Password from the Agent Authentication pop-up menu and enter a password. You can also choose Any from the Agent Authentication pop-up menu to permit any method of authentication. Note: Password authentication requires that the agent and controller use the same password. 12 Click Save and restart the service. Managing Client Access Server Admin in Mac OS X Server enables you to configure service access control lists (SACLs), which enable you to specify which users and groups have access to Xgrid and which administrators can manage it. Using SACLs enables you to add another layer of access control in addition to password and Kerberos authentication. Only users and groups listed in an SACL have access to its corresponding service. Setting SACL Permissions for Users and Groups You use Server Admin to set SACL permissions for users and groups to access Xgrid service. To set user and group SACL permissions for Xgrid service: 1 Open Server Admin and connect to the server. 2 Click Settings. 3 Click Access. 4 Click Services. 5 Select the level of restriction you want for the services: Chapter 2 Setting Up and Configuring Xgrid Service 35 To restrict access to all services, select "For all services." To set access permissions for individual services, select "For selected services below," then select a service from the Service list. 6 To provide unrestricted access to services, click "Allow all users and groups." 7 To restrict access to users and groups: a Select "Allow only users and groups below." b Click the Add (+) button to open the Users and Groups drawer. c Drag users and groups from the Users and Groups drawer to the list. 8 Click Save. Setting SACL Permissions for Administrators Use Server Admin to set SACL permissions for administrators to monitor and manage Xgrid service. To set administrator SACL permissions for Xgrid service: 1 Open Server Admin and connect to the server. 2 Click Settings. 3 Click Access. 4 Click Administrators. 5 Select the level of restriction you want for the services: To restrict access to all services, select "For all services." To set access permissions for individual services, select "For selected services below," then select a service from the Service list. 6 Open the Users and Groups drawer by clicking the Add (+) button. 7 From the Users and Groups drawer, drag users and groups to the list. 8 Set user permissions: To grant administrator access, choose Administer from the Permission pop-up menu next to the user name. To grant monitoring access, choose Monitor from the Permission pop-up menu next to the user name. 9 Click Save. 36 Chapter 2 Setting Up and Configuring Xgrid Service Managing Xgrid Service This section describes typical day-to-day tasks you might perform after you set up Xgrid service on your server. For information about initial setup, see "Setting Up Xgrid Service" on page 30. You can monitor and manage grids using Xgrid Admin. For more information, see Chapter 3, "Managing a Grid." Viewing Xgrid Service Status You can use Server Admin to view the status of Xgrid service. To view Xgrid service status: 1 Open Server Admin and connect to the server. 2 Click the triangle to the left of the server. The list of services appears. 3 From the expanded Servers list, select Xgrid. 4 Click Overview to see whether the service is running, when it started, agent and controller information, the number of jobs running and pending, and the amount of processor power available and used. 5 Click Logs to review the system, controller, and agent logs. Use the View pop-up menu to choose which log to view. Viewing Xgrid Service Logs You can use Server Admin to view the Xgrid system, controller, and agent logs for Xgrid service. To view logs: 1 Open Server Admin and connect to the server. 2 Click the triangle to the left of the server. The list of services appears. 3 From the expanded Servers list, select Xgrid. 4 Click Logs, then use the Show pop-up menu to choose System Log (Xgrid), Xgrid Controller Log, or Xgrid Agent Log. To search for specific entries, use the filter field above the log. From the Command Line You can also view the Xgrid service log at /var/log/system.log using the cat or tail commands in Terminal. Chapter 2 Setting Up and Configuring Xgrid Service 37 Stopping Xgrid Service You use Server Admin to stop Xgrid service. To stop Xgrid service: 1 Open Server Admin and connect to the server. 2 Click the triangle to the left of the server. The list of services appears. 3 From the expanded Servers list, select Xgrid. 4 Click the Stop Xgrid button (below the Servers list). From the Command Line You can also stop Xgrid service immediately by using the serveradmin command in Terminal. 38 Chapter 2 Setting Up and Configuring Xgrid Service 3 Managing a Grid 3 Use this chapter to learn how to use the Xgrid Admin application to manage grids, add controllers and agents, and work with jobs. After you set up an Xgrid controller, you can use Xgrid Admin to manage a grid. You can use Xgrid Admin on the server or on a remote computer that is running Mac OS X v10.4 or later. You can manage one or more computational grids with Xgrid Admin. A computational grid is a fixed group of agents with a dedicated queue. There can be multiple grids per controller but an agent can belong to only one grid. You cannot move an agent between grids while a job (or a task) is running. Using Xgrid Admin Xgrid Admin is a tool you use to monitor one or more grids and manage agents and jobs. With Xgrid Admin, you can:  Check the status of a grid and its activity, including the number of agents working and available, processing power in use and available, and the number of jobs running and pending  Add or remove controllers and grids to manage  See a list of agents in a grid and the CPU power available and in use for each agent  Add or remove agents in a grid  See a list of jobs in a grid, the date and time each job was submitted, its progress, and the active CPU power for the job  Remove jobs in a grid  Stop a job in progress  Restart a job that was stopped or is complete 39 Xgrid Admin provides controls in its graphical interface and menu commands for all of its options. Note: You can also use the Xgrid command-line tool to perform these tasks. For more information about using the command-line tool, see Chapter 4, "Planning and Submitting Xgrid Jobs." Status Indicators in Xgrid Admin Xgrid Admin provides status indicators, which are small color bubbles indicating the status of controllers, agents, and jobs. The color indicators are:  Colorless = controller or agent is offline, job is pending  Gray = job is submitting  Green = controller is connected, agent is working, job is running  Yellow = agent is available but not running  Red = agent is unavailable, job is failed or canceled  Blue = job is complete Managing the Xgrid Controller In general, you manage the Xgrid controller like any other service running on Mac OS X Server, using Server Admin to manage which processes are running and using Xgrid Admin to manage the agent and job queues on the controller. The amount of management required also depends on how many queues you have and the number (and temperament) of the users who submit jobs. Xgrid uses a simple first-in, first-out (FIFO) queue for scheduling each grid, which means that as the administrator you must obtain your colleagues' cooperation to make sure resources are allocated correctly among multiple users. For more information, see the following sections: Connecting to an Xgrid Controller You use Xgrid Admin to connect to an Xgrid controller. The controller must be reachable on any network by the administrative computer running Xgrid Admin. After Xgrid Admin is connected to the controller, you can view the status of its grid and manage its agents and jobs. 40 Chapter 3 Managing a Grid To connect to an Xgrid controller: 1 Open Xgrid Admin and do one of the following:  From the pop-up menu, choose the controller or enter its name and click Connect.  In the Controllers and Grids list, select the controller name and click Connect. 2 If necessary, select the correct authentication option, enter a password, and then click OK. Disconnecting from an Xgrid Controller You use Xgrid Admin to disconnect froman Xgrid controller in the Controllers and Grids list. To disconnect an Xgrid controller: 1 Open Xgrid Admin. 2 In the Controllers and Grids list, select a controller. 3 Click Disconnect. Adding an Xgrid Controller You use Xgrid Admin to add an Xgrid controller to the Controllers and Grids list. To add an Xgrid controller to the monitoring list: 1 Open Xgrid Admin. 2 Click Add Controller. 3 From the pop-up menu, choose a controller or enter its name and click Connect. 4 If necessary, select the correct authentication option, enter a password, and then click OK. Removing an Xgrid Controller You can easily remove an Xgrid controller from the Controllers and Grids list in Xgrid Admin. To remove an Xgrid controller: 1 Open Xgrid Admin. 2 In the Controllers and Grids list, select a controller. 3 Click Remove Controller. Chapter 3 Managing a Grid 41 Managing Agents Use Xgrid Admin to view, add, or delete agents. Xgrid Admin also uses status indicators to display the status of agents. Although Server Admin provides a simple interface for enabling Xgrid services on one server or across a rack of Xserve systems, it doesn't provide a way to configure Xgrid on desktop computers running Mac OS X v10.3 or later. If you are relying on volunteers to provide desktop agents, you can send instructions for enabling Xgrid from the Sharing pane of System Preferences. If the volunteers are using Mac OS X v10.3, you must first download the Xgrid Agent for Mac OS X v10.3 and then use the Xgrid pane of System Preferences. You can download the Xgrid Agent for Mac OS X v10.3 from: www.apple.com/server/macosx/xgrid.html If you administer a group of computers and want the computers to participate in a grid using Xgrid, you can use the following methods:  Apple Remote Desktop  SSH  NetBoot or NetInstall Apple Remote Desktop Apple Remote Desktop (ARD) v2.1 is a separate product available from Apple that integrates common administrative tasks across multiple computers (such as screen sharing, software installation, running UNIX scripts, and so on). You can use ARD to remotely run System Preferences on each computer but it is usually simpler to change the preferences once and then push the new preferences file (/Library/Preferences/com.apple.xgrid.agent.plist) to all relevant nodes. For more information, see the Apple Remote Desktop Administration guide at www.apple.com/server/documentation. SSH If you don't have ARD but you've set up SSH logins, you can do the same thing as ARD using the scp command-line tool (or rsync, if you've set that up). You can also use the xgridctl tool with the following command: $ ssh root@remotehost xgridctl agent start For more details, see the man pages for SSH, SCP, SFTP, or rsync in the Terminal application. 42 Chapter 3 Managing a Grid NetBoot or Network Install For large networks, it often makes sense to use a common system image that is mounted or installed by each agent to configure the agents. Although Xgrid isn't reason enough to use NetBoot, consider whether using Network Install would simplify your general administrator's tasks. If you use Netboot with Xgrid, all agents must have unique hostnames and must keep all files intact between reboots. For more information, see System Imaging and Software Update Administration at www.apple.com/server/documentation. Viewing a List of Agents You can see a list of agents for a controller in Xgrid Admin. To see a list of agents for an Xgrid controller: 1 Open Xgrid Admin. 2 In the Controllers and Grids list, select the grid. 3 Click Agents. 4 Select an agent in the list to see information about the CPU power and processors it uses. The color bubble to the left of the name shows each agent's status. For details, see "Status Indicators in Xgrid Admin" on page 40. Adding an Agent You can add an agent to a controller in Xgrid Admin. You can add agents that are offline. The agents will be available to the controller when the computers are online or when the controller administrator makes the agents active. To add an agent: 1 Open Xgrid Admin. 2 In the Controllers and Grids list, select the controller. 3 Click Agents. 4 Click the Add (+) button below the list of agents. 5 Enter a name for the agent and click OK. The agent is added to the list. The color bubble to the left of the name shows the agent's status. For details, see "Status Indicators in Xgrid Admin" on page 40. Chapter 3 Managing a Grid 43 Deleting an Agent You can delete an agent for an Xgrid controller in Xgrid Admin. To delete an agent: 1 Open Xgrid Admin. 2 In the Controllers and Grids list, select the controller. 3 Click Agents. 4 Click the Delete (­) button below the list of agents. Note: If you delete an agent that you know is on the local subnet and is configured to attach to that controller, wait a few moments and it will reappear in the list. If the agent doesn't reappear, use the Add (+) button and enter its name to retrieve it. Managing Jobs You use Xgrid Admin to manage jobs after they are submitted by a client. You cannot move a job between grids. Viewing a List of Jobs You can see a list of jobs in Xgrid Admin. To see a list of jobs: 1 Open Xgrid Admin. 2 In the Controllers and Grids list, select the controller. 3 Click Jobs. 4 Select a job in the list to see details of that job. Stopping a Job You can stop a job in Xgrid Admin. To stop a job: 1 Open Xgrid Admin. 2 In the Controllers and Grids list, select the controller. 3 Click Jobs. 4 Select the job you want to stop. 5 Click the Stop button below the list of jobs. 44 Chapter 3 Managing a Grid Repeating or Restarting a Job You can repeat a job or restart a stopped job in Xgrid Admin. To repeat or restart a job: 1 Open Xgrid Admin. 2 In the Controllers and Grids list, select the controller. 3 Click Jobs. 4 Select the job you want to repeat or restart. 5 Click the Start button below the list of jobs. Deleting a Job You can delete a job in Xgrid Admin. To delete a job: 1 Open Xgrid Admin. 2 In the Controllers and Grids list, select the controller. 3 Click Jobs. 4 Select the job you want to delete. 5 Click the Delete (­) button below the list of jobs. Adding a Grid You use Xgrid Admin to add a grid to an Xgrid controller in the Controllers and Grids list. To add a grid: 1 Open Xgrid Admin. 2 Select the Xgrid controller you want to add the grid to. 3 Click the Add (+) button below the Controller and Grids list. 4 In the pop-up menu, enter a name for the new grid and click OK. Chapter 3 Managing a Grid 45 Deleting a Grid You use Xgrid Admin to remove a grid from an Xgrid controller in the Controllers and Grids list. To delete a grid: 1 Open Xgrid Admin. 2 In the Controllers and Grids list, select the grid. 3 Click the Action pop-up menu below the Controller and Grids list and select Remove Grid. 4 Click OK. Monitoring Grid Activity You can quickly view the activity of a grid in Xgrid Admin. You can also view agents and job activity using Xgrid Admin. For more information, see "Viewing a List of Agents" on page 43 and "Viewing a List of Jobs" on page 44. To monitor the activity of a grid: 1 Open Xgrid Admin. 2 In the Controllers and Grids list, select the Xgrid controller. 3 Click Overview to see the number of agents, the amount of processor power available and used, and the number of jobs running and pending. 46 Chapter 3 Managing a Grid 4 Planning and Submitting Xgrid Jobs 4 Use this chapter to learn how to use Xgrid command-line tools and the Terminal application to submit jobs to a grid and to get information about jobs. After you configure an Xgrid controller and add agents to a grid, you can use the Terminal application to send a job to the grid. Structuring Jobs for Xgrid Carefully planning and structuring a job can result in efficient use of the grid. For example, the best structure for a job that requires multiple searches of a large database may be to divide the database into multiple sections and provide a section to each agent in the grid. About Job Styles Different styles of jobs often require different handling. Similarly, the way a job is structured influences how efficiently the grid completes it. Consider the following job styles:  Everything in one single large job, with numerous small tasks.  Everything divided into medium-sized jobs, where each job has roughly as many tasks as there are nodes in the grid. (This type of job is usually created by a meta job script, which divides the job into smaller chunks, each of which is a job in itself.)  An entire workflow composed of several interrelated jobs. Deciding how to structure a job can involve experimentation to discover the best way to complete it. For example, you might create a simple, small version of a job in two styles, such as by planning all tasks in one job or by subdividing into multiple tiny jobs. Running both experimental jobs under similar conditions in the grid will give you a good idea of which job style is better suited to those conditions. 47 About Job Failure Xgrid jobs can rely on message-passing interface (MPI) APIs. For jobs that rely on MPI, if a single task fails, the entire job fails and must be resubmitted. Therefore you should not use MPI-based jobs on grids with high task-failure rates. Jobs that are more parallel in nature are generally unaffected by occasional task failures. Tasks are typically reassigned to other available agents to complete the job. Most jobs fall into this category. Submitting a Job You submit jobs to a grid using the command-line tool and Terminal. Example code is available on the Apple developer website (developer.apple.com) for alternative methods of submitting jobs. Also If you have Developer Tools installed you can view the examples located in /Developer/Examples/Xgrid/. For more information about the syntax and options for the xgrid command-line tool, see the xgrid man pages. Some developers and organizations offer specialized applications for submitting jobs to a grid. Or you can create such an application using Apple's developer tools for Xgrid. When determining whether to use the xgrid command-line tool or another method for submitting jobs, consider these points:  If the job is simple, use the command-line tool.  If you use a shell script, use the command-line tool.  If you want to use Xgrid as part of an application with a graphical user interface (GUI), use the Xgrid API to create the GUI or incorporate it in an existing application. For more information about the API, see the Xgrid Reference at: developer.apple.com/documentation Examples of Xgrid Job Submission and Results Retrieval The following Terminal commands are examples of jobs a client can submit to the controller. $ xgrid -h -p -job submit /bin/echo "Hello, World!" This job runs /bin/echo on the controller and agent systems with the "Hello, World!" parameter. $ xgrid -h -p -job results -id This command shows the results of the job with the id indicated. For an executable shell script marked hello.sh: #!/bin/sh /bin/echo "Hello, World!" 48 Chapter 4 Planning and Submitting Xgrid Jobs The following command copies the shell script hello.sh to the Xgrid controller and agent systems and runs the script. /bin/echo must be installed on the agent system. The hello.sh script must have its executable bit set before it can execute. xgrid -h -p -job submit hello.sh Viewing Job Status You can monitor jobs in Xgrid Admin (for details, see "Managing Jobs" on page 44) or with the command-line tool. The following commands in Terminal provide job status: $ xgrid -h -p -job list $ xgrid -h -p -job attributes -id Retrieving Job Results You can retrieve job results using the command-line tool. The following commands in Terminal retrieve job results. $ xgrid -h -p -job results $ xgrid -h -p -job results id Chapter 4 Planning and Submitting Xgrid Jobs 49 50 Chapter 4 Planning and Submitting Xgrid Jobs