Using HP Systems Insight Manager to achieve high availability for Microsoft Team Foundation Server

Transcription

1 Using HP Systems Insight Manager to achieve high availability for Microsoft Team Foundation Server Executive summary... 2 Audience... 2 Architecture... 3 Prerequisite... 4 Deploying AT servers... 5 Configuring NLB... 6 Configuring NLB on TFSAT Configuring NLB on TFSAT Verifying the configuration Registering the cluster name Installing and configuring TFS AT Installing and configuring HP SIM Configuring the RDP job Installing remote agents on the AT servers Creating the RDP job Configuring HP SIM and creating HP SIM tasks Discovering the AT servers Setting up hardware polling Creating custom commands Setting up automatic event handling Testing AT server failover About HP and Microsoft For more information... 53

2 Executive summary Microsoft Team Foundation Server (TFS) is an element of Microsoft Visual Studio 2005, teamoriented, server-based software that is designed to manage the full application development life cycle, including modeling, testing, and project management. TFS is a workflow collaboration engine that recognizes that all work involved in a software project is symbiotically related, no matter what form it happens to take. The integrated approach of TFS allows decisions to be made based on real-time information from a single, comprehensive data source. This solution guide provides detailed guidelines on providing high availability for the TFS Application Tier using HP Systems Insight Manager (HP SIM) and Microsoft Network Load Balancing (NLB). Audience This solution guide is directed at developers, testers, software development managers, and IT staff and administrators who are seeking to implement or propose the implementation of a development solution based on Microsoft Visual Studio Team System. The goal is to address audience concerns that such a solution be robust enough to support the development of mission-critical software. 2

3 Architecture In the large enterprise high availability environment, the Team Foundation Server (TFS) solution can be distributed into two major parts, the TFS Data Tier (DT) and TFS Application Tier (AT). This solution guide focuses on a high availability solution for the AT using HP Systems Insight Manager (HP SIM). The solution uses two servers for the AT: one server functions as the primary AT server, the second as a hot standby server. If a failure were to prevent the primary server from responding to a client request, the standby server would automatically replace the failed server as primary server. Figure 1 details the configuration implemented and tested by HP. Figure 1. TFS server configuration Client Clients NLB VTFSAT Client Windows Core Infrastructure TFSDT TFSAT01 (Primary) TFSAT02 (Standby) Cluster VTFSDT TFSDT x BL25p MGMT x BL45p SQL Server: Back-end database cluster EVA4000/MSA1500/MSA1000 Fiber channel based SAN for external storage Note: The network is a management network used exclusively by HP SIM. One of the challenges of deploying TFS is that high availability at the AT layer must be achieved without implementing standard load-balancing. The current implementation of the AT layer is stateful; if traffic is diverted from the primary AT server for any reason even if it is to a properly configured standby AT server then system functionality breaks down. In other words, there can only be one primary AT server at any given point in time. 3

4 The solution described in this solution guide leverages a particular implementation of Microsoft Network Load Balancing (NLB) as a load balancing mechanism. Rather than running both AT servers simultaneously as members of the NLB cluster, only one server is ever running within the NLB cluster at any time even if both servers are physically turned on. In this case, NLB does not actually balance load across multiple application servers. Rather, it provides a virtualization context, so that either of two servers may respond to the same virtual server name or virtual IP address. NLB also provides a scripting mechanism that allows for one server to be turned off (i.e. no longer accepting requests) and another to be turned on (i.e. to begin accepting requests). It is by means of this scripting mechanism that this solution enforces the requirement that only one AT server be active at any given moment, and it is by means of the virtual server name and virtual IP address provided by NLB that this primary AT server can be one of two different servers at any given point in time. In Figure 1, therefore, the following default cluster convergence states apply: The secondary AT server, TFSAT02, is off The primary AT server, TFSAT01, is on To effect high availability, HP SIM and HP ProLiant Essentials Rapid Deployment Pack (RDP) are leveraged to run two custom commands on the secondary AT server in the event the primary AT server should fail. The custom commands are: 1. Mark the secondary AT server as the active primary AT server. 2. Start up NLB on the secondary AT server now that it is the only server that can converge in the NLB cluster context. The end result is that the secondary AT server can quickly come online after a primary AT server failure and, moreover, it can come online in a controlled fashion that works within the limitations of the current implementation of TFS. The remainder of this solution guide details the procedures used to configure and test this solution. Prerequisite Note: This solution guide assumes a standard installation of the TFS DT servers using a clustered instance of Microsoft SQL Server This installation is outside the scope of this document. The solution requires three servers to provide services at the AT 1 : two servers for the TFS AT services (TFSAT01 and TFSAT02) and one server configured as a management server (MGMT). All three servers must be members of the same domain, in this case VSTSTEST.COM; each requires the following software: Microsoft Windows Server 2003 and Windows Server 2003 Service Pack 1. Standard Edition or Enterprise Edition may be used at the Application Tier. Note: If desired, Windows Server 2003 R2 may be used instead. 1 Additional servers are required for the DT and the remaining infrastructure 4

5 The latest security hotfixes for Windows Server 2003, available at Microsoft Internet Information Services (IIS) 6.0 with ASP.NET installed. IMPORTANT: Microsoft FrontPage Server Extensions must not be installed. Windows SharePoint Services with Service Pack 2 On the management server (MGMT): RDP Windows Edition (RDP) Note: Support and documents for RDP are available at p/documentation.html. As best practice, HP recommends configuring the two AT servers with three network interfaces each: one for client-side connections, one for TFS DT connections, and one for the management network. In this example, server TFSAT01 has three different IP addresses on three different networks: The client-side IP address is The TFS DT-facing IP address is The management IP address is Deploying AT servers The deployment process for AT servers includes the following stages: Configuring NLB Installing and configuring TFS AT Installing HP SIM on the management server Configuring a RDP job Configuring HP SIM to monitor the status of AT servers; creating custom commands and event handling tasks that can be used, in conjunction with the RDP job, to automatically replace a failed AT server Testing AT server failover Each of these stages is detailed below. 5

6 Configuring NLB This solution guide does not articulate all NLB configuration details which are readily available from Microsoft but, rather, details just what is necessary to apply NLB functionality in the context of the TFS solution. Note: Microsoft has published many articles describing the installation and configuration of NLB. For detailed information about NLB functionality, see v/deploy/confeat/nlbovw.mspx. This section provides instructions for the following: Configuring NLB on TFSAT01 Configuring NLB on TFSAT02 Verifying the configuration Registering the cluster name 6

7 Configuring NLB on TFSAT01 The procedure for configuring NLB on TFSAT01, the primary AT server, is as follows: 1. Click Start Control Panel Network Connections. Identify the Network Interface Card (NIC) that faces the client this is the NIC that will be loadbalanced using NLB. In this example, the appropriate NIC has IP address Rightclick on the icon for this NIC, then select Status. In the NIC Properties dialog box (shown in Figure 2), click General Properties. Figure 2. Invoking the Properties dialog box 7

8 2. Using the Properties dialog box, select and highlight Network Load Balancing in the This connection uses the following items list box, then click the Properties button (as shown in Figure 3). Figure 3. Selecting Network Load Balancing 3. In the Network Load Balancing Properties dialog box (shown in Figure 4), under the Cluster Parameters tab, enter the virtual IP address. In this example, this IP address is Also, enter the appropriate Subnet mask and virtual Full Internet name for the AT server NLB configuration. Note: Later in the configuration process, Full Internet name is used as the virtual application server name. Note: A Class C subnet mask is used in our example. In a production deployment, the appropriate production subnet mask should be used. 8

9 Set the Cluster operation mode to Unicast or Multicast, as appropriate for the environment. While it is not a requirement, if this is standard operating procedure for your production environment, check Allow remote control and provide a suitable password. Figure 4. Specifying Cluster Parameters properties for NLB 9

10 4. In the Network Load Balancing Properties dialog box, under Host Parameters tab (shown in Figure 5), set Priority to 1 for TFSAT01. Assign the physical IP address and Subnet mask for TFSAT01. In this example, the values are and , respectively. Click the OK button. Note: The Default state for TFSAT01 should be Started. Figure 5. Specifying Host Parameters properties for NLB 10

11 5. In the Properties dialog box (shown in Figure 6), select and highlight Internet Protocol (TCP/IP) in the This connection uses the following items list box, then click the Properties button. Figure 6. Specifying Internet Protocol (TCP/IP) 11

12 6. In the Internet Protocol (TCP/IP) Properties dialog box, under the General tab (shown in Figure 7), select Use the following IP address and enter the physical IP address and Subnet mask for TFSAT01. In this example, the values are and , respectively. Click the Advanced button. Figure 7. Specifying General Properties for TCP/IP 12

13 7. In the Advanced TCP/IP Settings dialog box, under the IP Setting tab (shown in Figure 8), in the IP address list box, click the Add button to add the NLB virtual IP address and subnet mask. In this example, these values are and , respectively. Click the OK button on each of the three open dialog boxes. This completes NLB configuration on TFSAT01. Figure 8. Specifying Advanced Properties for TCP/IP 13

14 Configuring NLB on TFSAT02 The procedure for configuring NLB on TFSAT02, the hot standby AT server, is the same as the procedure above for configuring NLB on TFSAT01, with the following exception: Specify as the physical IP address for TFSAT02 Note: The virtual IP address for TFSAT02 is , the same as that for TFSAT01. Note: Values specified in this example are for demonstration purposes only. For a deployment in a production environment, always use the correct production IP addresses and subnet masks. Verifying the configuration Once completed, the NLB configuration should be verified. To obtain NLB status, type the following on the Windows command line: nlb query Registering the cluster name Finally, the virtual host name for the NLB cluster should be registered with DNS. If using Active Directory to host DNS, perform the following procedure: 1. Open the DNS console on a domain controller. 2. Expand Forward Lookup Zones under the domain controller server name. 3. Then, right-click the domain name (VSTSTEST.COM, for example) and select New Host (A). 4. In the New Host dialog box, enter the virtual application server name and the virtual application server IP address. In this example, enter VTFSAT and , respectively. 5. Click the Add Host button. The future TFS client application will use virtual server name VTFSAT in its configuration. Make sure that the virtual IP address and virtual server name resolution both function appropriately. Tools like nslookup and ping are very useful for this purpose. 14

15 Installing and configuring TFS AT Note: This installation procedure assumes TFS AT is installed under the Program Files directory in the default TFS installation directory. A complete AT installation procedure is documented on the TFS CD. After being inserted, the TFS CD automatically launches the Team Foundation Server Setup wizard. If you wish to review the installation procedure, select Review the Installation Guide on the initial wizard setup screen. Information on installing the AT is located in the Overview of Team Foundation Server Dual-Server Deployment chapter, in the section entitled Installing Team Foundation Server (services). To view the installation procedure, click the article entitled, How to: Installing Team Foundation Server (services). Once this installation is complete, you must activate the primary AT server, TFSAT01. To activate the virtual AT server name as the active AT server, launch a Windows command line, CMD.EXE. At the command line, type the following: %ProgramFiles%\Microsoft Visual Studio 2005 Team Foundation Server\Tools\TfsAdminUtil.exe activateat noprompt VTFSAT Installing and configuring HP SIM In this example, HP SIM is installed on the management server, MGMT. HP SIM can be downloaded from More information on the HP SIM installation process is available at Configuring the RDP job With RDP running on the management server, you can create a job to be deployed on the hot standby server to replace the primary AT server in the event the primary AT server should fail. Note: In order for this procedure to work, the hot standby server must be visible from the RDP Deployment Console, allowing RDP to send the job to this server for execution. Perform the following procedures: Installing remote agents on the AT servers Creating the RDP job 15

16 Installing remote agents on the AT servers 1. On the MGMT desktop, double-click the Deployment Console icon to launch RDP, invoking the Deployment Console (shown in Figure 9). Figure 9. RDP Deployment Console 16

17 2. From the RDP Deployment Console, select Tools, then Remote Agent Installer, as shown in Figure 10. Figure 10. Invoking Remote Agent Installer 17

18 3. In the Remote Agent Installer dialog box (shown in Figure 11), enter the username and password of a user with administrative rights to TFSAT01 and TFSAT02, then click the Next button. Figure 11. Entering the desired user credentials 18

19 4. Click the Next button to accept the default install directory (as shown in Figure 12). Figure 12. Accepting the default install directory 19

20 5. Select Add client(s) to default group (as shown in Figure 13), then click the Next button. Figure 13. Selecting the option to add clients 20

21 6. In the Remote Agent Installer dialog box, click the Add button (as shown in Figure 14) so that you can specify the clients you wish to be added to the list of selected clients. Figure 14. Clicking Add so that you can select the clients you wish to add to the list 21

22 7. From the Browse dialog box (shown in Figure 15), review the servers available on the selected network. Figure 15. Noting that servers TFSAT01 and TFSAT02 are available 22

23 8. Select server TFSAT01 (as shown in Figure 16), then click the OK button. Figure 16. Selecting server TFSAT01 to be added to the list 23

24 9. Repeat Steps 6 8 and to add server TFSAT02 to the list. Verify that both servers have been added (as shown in Figure 17), then click the Finish button. Figure 17. Verifying that you have added both servers to the list 24

25 10. The agent is successfully installed when the status message, The install completed successfully, appears in the dialog next to the server name (see Figure 18). After successfully installing the agent, click the Exit Install button (shown in Figure 18). Figure 18. Verifying that the install completed successfully 25

26 11. Now that the agent install is complete, verify that servers TFSAT01 and TFSAT02 have automatically been added to the New Computers group in the RDP Deployment Console (as shown in Figure 19). Figure 19. Verifying that the AT servers have been added to the RDP Deployment Console 26

27 Creating the RDP job 1. Right-click System Jobs in the Jobs panel of the RDP Deployment Console and select New Job (as shown in Figure 20). Figure 20. Selecting the option to create a new RDP job 27

28 2. Create a new job named Start VTFSAT. Once this is done, double-click the Start VTFSAT job (as shown in Figure 21). Figure 21. Selecting the Start VTFSAT job 28

29 3. In the Job Properties dialog box, click Add>> button (as shown in Figure 22). Figure 22. Selecting the Add>> button in the Job Properties dialog 4. Select Run Script (as shown in Figure 23). Figure 23. Selecting the Run Script command 29

30 5. In the Run Script dialog box, click Run this script and enter the following (as shown in Figure 24): "%ProgramFiles%\Microsoft Visual Studio 2005 Team Foundation Server\Tools\TfsAdminUtil.exe" activateat -noprompt VTFSAT. This is the script that will activate a secondary TFS AT server when such activation becomes necessary. Figure 24. Entering a script in the Run Script dialog box In Choose the script operating system, select Windows, then click the Next button. Note: TfsAdminUtil.exe uses the virtual application server name. 30

31 6. Provide additional information for the script (as shown in Figure 25). In Script Run Location, click On the client computer. In Client Run Environment, select Production Client-installed OS (Windows/Linux), then Specific User. Figure 25. Providing additional script information 7. Enter the username and password for the user context desired to execute the script (as shown in Figure 26), then click the OK button. Figure 26. Providing user credentials 31

32 8. Verify that a Run Script task has been added to the Job Properties dialog box (as shown in Figure 27), then click the OK button. Figure 27. Verifying that a Run Script task now appears in the Start VTFSAT job 9. Verify that the Start VTFSAT job appears in the RDP Deployment Console. This job is now ready to be used in conjunction with HP SIM. It can also be run manually, but the goal is to enable it to be kicked off by HP SIM itself. This process is described below. Figure 28. The Start VTFSAT job is now ready for use 32

33 Configuring HP SIM and creating HP SIM tasks This section provides detailed information on configuring HP SIM and monitoring the primary TFS AT server for any failures. It also shows how to configure HP SIM to automatically handle the failure by bringing the secondary TFS AT server online without user interaction. The following procedures are included: Allowing HP SIM to discover the AT servers Set up a task to poll AT server hardware Creating custom commands to start the hot standby server using the RDP job created earlier Setting up automatic event handling tasks to run the custom commands when HP SIM detects a critical event on the primary AT server Discovering the AT servers Note: If you are using an existing HP SIM installation, it may have already discovered the TFS AT servers. In this case, skip to the next subsection, Setting up hardware polling. 33

34 1. From the management server, MGMT, launch the HP SIM console (shown in Figure 29). Log in to the console using the appropriate credentials. Figure 29. Logging in to HP SIM 34

35 2. Initially, a new HP SIM installation does not recognize the AT servers; as a result, HP SIM must be allowed to discover servers and other hardware installed. Here we describe how to use HP SIM to discover the TFS AT servers on the network where they are deployed. From the HP SIM console, click Options, then select Discovery (as shown in Figure 30). Figure 30. Selecting the Discovery option in HP SIM 35

36 3. In the Manual tab, enter the name or IP address of AT server you wish HP SIM to discover. In this example, enter for TFSAT01, then click the Add System button (as shown in Figure 31). Repeat this step for TFSAT02 using IP address Figure 31. Allowing HP SIM to discover server TFSAT01 Setting up hardware polling After allowing HP SIM to discover the AT servers, you should set up HP SIM to poll the servers for their current status automatically and on a specified schedule. Note: If you are using an existing HP SIM installation, it may already be configured to discover servers on the network on the subnet in which the AT servers are installed. In this case, skip the discovery steps 2 and 3, described above. Some HP SIM installations are also configured to enable Hardware Status Polling. Whether or not this is the case, the TFS AT servers must be added as servers whose hardware status is to be polled. Whether or not Hardware Status Polling is already enabled as a general IT policy, it is necessary to follow the steps below to ensure it is specifically enabled for the TFS AT servers themselves. 36

37 1. From the HP SIM menu bar, click Options, then Status Polling and select Hardware Status Polling (as shown in Figure 32). Figure 32. Selecting Hardware Status Polling 2. Set up the target systems for hardware status polling in this example, configure HP SIM to poll both AT servers. In Step 1: Verify Target Systems, check both servers (as shown in Figure 33), then click the Next button. Figure 33. Selecting both AT servers as hardware status polling targets 37

38 3. In Step 2: Select Protocol Settings, click Schedule to accept default protocol settings. Figure 34. Accepting the default protocol settings 38

39 4. In Step 3: Schedule Task, specify a name for the polling task name TFSAT Server HW Polling, in this example and refine the schedule so that the servers are polled every 1 minute. After setting these values, click Done. Note: With these settings, HP SIM receives AT server status updates every minute. As a result, if the primary AT server were to fail, HP SIM would be able to start the hot standby server in, at worst case, one to two minutes. Figure 35. Naming the task and refining the schedule 39

40 5. Review the newly-created polling task shown in All Scheduled Tasks. Figure 36. The newly-created TFSAT Server HW Polling task now appears in the All Scheduled Tasks list Creating custom commands After setting up hardware polling, you can now set up custom commands to be automatically executed by HP SIM in the event the primary AT server should fail. These commands are used to start the hot standby server, setting it up as a new primary AT server to replace the failed system. One command is invoked if TFSAT01 were to fail; the second command is invoked if TFSAT02, now the primary AT server, were to fail. 40

41 Follow this procedure to create the custom commands: 1. On the HP SIM menu bar, click Tools, select Custom Commands and then New Custom Command (as shown in Figure 37). Figure 37. Invoking the option to create a new custom command 2. Specify a name for the new custom command (as shown in Figure 38) Start TFSAT01 in this example. In Command (Executable path and file name), enter the following: "%ProgramFiles%\Altiris\eXpress\Deployment Server\axSched.exe" In Parameters, enter the following: TFSAT01 "Start VTFSAT" /t " :00" Then click the OK button. This command tells axsched.exe to run the RDP job Start VTFSAT, which was configured above. Note: The axsched.exe program is a command-line utility that allows RDP jobs to be associated with computers or groups within the RDP console and run. By setting the start date and time in the past, the job is automatically configured to run immediately. 41

42 Figure 38. Creating new custom command Start TFSAT01 42

43 3. Repeat Steps 1 and 2 to create Start TFSAT02, the second new custom command (as shown in Figure 39). In Command (Executable path and file name), enter the following: "%ProgramFiles%\Altiris\eXpress\Deployment Server\axSched.exe" In Parameters, enter the following: TFSAT02 "Start VTFSAT" /t " :00" then click the OK button. Figure 39. Creating new custom command Start TFSAT02 43

44 4. On the HP SIM menu bar, click Tools and select Custom Commands. Then, click Manage Custom Commands (as shown in Figure 40). Figure 40. Invoking the option to Manage Custom Commands 5. Review the newly-created custom commands (shown in Figure 41). Figure 41. Reviewing the custom commands 44

45 Setting up automatic event handling When the primary server experiences a critical event and is no longer available, HP SIM can respond automatically if configured appropriately. Perform the following steps to set up automatic event handling tasks that will run the custom commands you have just created: 1. On the HP SIM menu bar, click Options, select Events, and click Automatic Event Handling (as shown in Figure 42). Figure 42. Invoking the option to configure automatic event handling 2. Select New Task (as shown in Figure 43) so that you can specify event-handling attributes. Figure 43. Invoking a new task 45

46 3. In the New Task screen, select with event and system attributes that I will specify, then click Next (as shown in Figure 44). Figure 44. Indicating your intent to specify event and system attributes for the new task 4. Specify the Task name if TFSAT01 fails in this example and click Next (as shown in Figure 45). Figure 45. Specifying a name for the new task 46

47 5. Specify primary server events that will trigger the execution of the task. Many options are available; in this example, however, HP specified events deemed by HP SIM to be Critical or Major (as shown in Figure 46). Typically, such events would indicate that the primary server is no longer online and should be replaced by the hot standby server. Click Next. Figure 46. Specifying events that would cause the new task to be executed 47

48 6. Specify the system to be monitored. In this example, HP specified and TFSAT01 (as shown in Figure 47), allowing the system to be monitored by both IP address and server host name. Click Next. Figure 47. Specifying the system to be monitored 7. Select the action to be taken should an event occur. To specify that the custom command created earlier should be executed, check Run custom command and enter the name of the command, Start TFSAT02 (as shown in Figure 48). Click Next. Figure 48. Indicating that a custom command must be run when a specified event occurs 48

49 8. HP SIM allows you to select a time filter, if desired, so that you can restrict event handling to specific days or specific times. To allow 24x7 monitoring, do not select the Use time filter option (shown in Figure 49); click Next. Note: The requirements of your production environment may dictate the need for a time filter. Whether or not this is configured depends on the specific level of service being provided and IT policy of the organization deploying Microsoft Visual Studio Team System (VSTS). Figure 49. Choosing to allow 24x7 monitoring; no time filter is selected 49

50 9. Review a summary of the new automatic event handling task (shown in Figure 50), then click Finish. Figure 50. Reviewing a summary of the new task 10. Repeat Steps 1 9 to specify automatic event handling to accommodate the failure of TFSAT02. Create a task named If TFSAT02 fails. 11. After you have specified the second task, review the newly-created automatic event handling in the Manage Tasks view (shown in Figure 51). Figure 51. Newly-created automatic event handling appearing in the HP SIM Manage Tasks view 50

51 Testing AT server failover After following the process described above to deploy TFSAT01 and TFSAT02, HP verified that the hot standby (TFSAT02) came online automatically after a primary server (TFSAT01) failure. The following procedure was used: 1. Simulate the failure of the primary AT server, TFSAT01. This can be accomplished in several ways, for example: Press and hold the server s power button for five seconds Use HP Integrated Lights-Out (ilo) to turn off the server If TFSAT01 is a server blade, simply pull the blade from its enclosure 2. Hardware polling occurs automatically within one minute of server failure. Monitor the HP SIM Task Results screen (as shown on Figure 52). Figure 52. The server hardware polling task was automatically launched and completed successfully 51

52 3. Continue monitoring the Task Results screen. HP SIM has become aware of the failure of TFSAT01; the automatic event handling task if TFSAT01 fails now launches and executes its custom command (as shown in Figure 53). In this example, the custom command starts up NLB on TFSAT02 and causes TFSAT02 to replace TFSAT01 as primary AT server. Note: Though the specifics are beyond the scope of this document, it is worth mentioning that Systems Insight Manager can also be configured to send out automatic notification via or pager to inform system administrators that a failover has occurred. Figure 53. Demonstrating that a failure has been detected and that, in response, task if TFSAT01 fails has been launched automatically 52

53 About HP and Microsoft The HP and Microsoft alliance is one of the oldest of its kind in the industry with 20 years of combined marketplace leadership. The HP and Microsoft Alliance can provide the adaptability, credibility, and stability you are looking for. Our focus on innovation and synchronization, our technical expertise and track record, and our stability-driven approach enable us to offer proven frontline innovation for the way you run your business, for the way you work, and for the way you experience and enjoy technology. For more information Microsoft Visual Studio, Microsoft Visual Studio Team System, msdn.microsoft.com/vstudio/teamsystem/ HP ProLiant servers, HP BladeSystem, HP StorageWorks, HP ProLiant Essentials software, Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice. The only warranties for HP products and services are set forth in the express warranty statements accompanying such products and services. Nothing herein should be construed as constituting an additional warranty. HP shall not be liable for technical or editorial errors or omissions contained herein. Microsoft and Windows are U.S. registered trademarks of Microsoft Corporation. 5/2006