How to: Configure a Report Server on a Network Load Balancing Cluster

If you are configuring a report server scale-out to run on a Network Load Balancing (NLB) cluster, you must do the following:

  • Ensure that the NLB cluster is accessible through a virtual server name that maps to the virtual server IP address. A virtual server name is necessary so that you can configure a single point of entry to the NLB cluster. When you configure a URL for each report server instance, you will specify the virtual server name as the host.

  • Configure view state validation to support interactive report viewing. Interactive reports are typically rendered numerous times during a single user session to visualize new or different data in response to user actions. By configuring view state validation, continuity is preserved within the user session regardless of which report server services the actual request.

Reporting Services does not provide functionality for load balancing a scale-out deployment or for defining a single point of access through a shared URL. You must implement a separate software or hardware NLB cluster solution to support a Reporting Services scale-out deployment.

You can install Reporting Services on nodes that are already part of an NLB cluster, or you can configure a scale-out deployment first and then install cluster software.

Steps for Report Server Deployment on an NLB Cluster

Use the following guidelines to install and configure your deployment:



More information


Before you install Reporting Services on server nodes in an NLB cluster, check the requirements for scale-out deployment.

Planning for Scale-Out Deployment in SQL Server Books Online


Configure the NLB cluster and verify it is working correctly.

Be sure to map a host header name to the virtual server IP of the NLB cluster. The host header name is used in the report server URL, and is easier to remember and type than an IP address.

For more information, see the Windows Server product documentation for the version of the Windows operating system that you run.


Install Reporting Services in files-only mode on nodes that are already part of a NLB cluster, and configure the report server instances for scale-out deployment.

The scale-out that you configure might not respond to requests that are directed to the virtual server IP. Configuring the scale-out to use the virtual server IP occurs at a later step, after you configure view state validation.

How to: Configure a Report Server Scale-Out Deployment (Reporting Services Configuration)


Configure view state validation.

For best results, perform this step after you configure the scale-out deployment, and before you configure the report server instances to use the virtual server IP. By configuring view state validation first, you can avoid exceptions about failed state validation when users attempt to access interactive reports.

How to Configure View State Validation in this topic.


Configure Hostname and UrlRoot to use the virtual server IP of the NLB cluster.

How to Configure Hostname and UrlRoot in this topic.


Verify the servers are accessible through the host name you specified.

Verify Report Server Access in this topic.

How to Configure View State Validation

To run a scale-out deployment on an NLB cluster, you must configure view state validation so that users can view interactive HTML reports. You must do this for the report server and for Report Manager.

View state validation is controlled by the ASP.NET. By default, view state validation is enabled and uses the identity of the Web service to perform the validation. However, in an NLB cluster scenario, there are multiple service instances and web service identities that run on different computers. Because the service identity varies for each node, you cannot rely on a single process identity to perform the validation.

To work around this issue, you can generate an arbitrary validation key to support view state validation, and then manually configure each report server node to use the same key. You can use any randomly generated hexadecimal sequence. The validation algorithm (such as SHA1) determines how long the hexadecimal sequence must be.

  1. Generate a validation key and decryption key by using the autogenerate functionality provided by the .NET Framework. In the end, you must have a single <machineKey> entry that you can paste into the Web.config file for each Report Manager instance in the scale-out deployment.

    The following example provides an illustration of the value you must obtain. Do not copy the example into your configuration files; the key values are not valid.

    <machineKey validationKey="123455555" decryptionKey="678999999" validation="SHA1" decryption="AES"/>
  2. Open the Web.config file for Report Manager, and in the <system.web> section paste the <machineKey> element that you generated. By default, the Report Manager Web.config file is located in \Program Files\Microsoft SQL Server\MSRS10_50.MSSQLSERVER\Reporting Services\ReportManager\Web.config.

  3. Save the file.

  4. Repeat the previous step for each report server in the scale-out deployment.

  5. Verify that all Web.Config files in the \Reporting Services\Report Manager folders contain identical <machineKey> elements in the <system.web> section.

How to Configure Hostname and UrlRoot

To configure a report server scale-out deployment on an NLB cluster, you must define a single virtual server name that provides a single point of access to the server cluster. Then register this virtual server name with the Domain Name Server (DNS) in your environment.

After you define the virtual server name, you can configure the Hostname and UrlRoot properties in the RSReportServer.config file to include the virtual server name in the report server URL.


The UrlRoot property affects the URL that users will see in e-mail that is sent by a Reporting Services subscription. If the UrlRoot property remains empty in the RSReportServer.config file, the URL that is visible in e-mail will contain the physical computer name instead of the URL of the NLB virtual server. To avoid the potential disclosure of the physical computer name to malicious users that may receive the subscription, change the UrlRoot property to the appropriate NLB virtual server name.

Configure the Hostname property when you are using wildcard URL reservations in your reporting environment. When you specify the Hostname property to be the virtual server name of the NLB server, network traffic for the reporting environment is directed to the NLB server. The NLB then distributes requests among the report server nodes.

Additionally, configure the UrlRoot property so that report links work in reports that have been exported to static reports, such as in an Excel or PDF format, or in reports that are generated by subscriptions, such as e-mail subscriptions.

If you integrate Reporting Services with Windows SharePoint Services 3.0 or Office SharePoint Server 2007, or you host your reports in a custom Web application, you might need to configure only the UrlRoot property. In this case, configure the UrlRoot property to be the URL of the SharePoint site or Web application. This will direct network traffic for the reporting environment to the application that handles the reports rather than to the report server or NLB cluster.

Do not modify ReportServerUrl. If you modify this URL, you will introduce an extra roundtrip through the virtual server each time an internal request is handled. For more information, see URLs in Configuration Files (Reporting Services). For more information about editing the configuration file, see How to: Modify a Reporting Services Configuration File in SQL Server Books Online.

  1. Open RSReportServer.config in a text editor.

  2. Find the <Service> section, and add the following information to the configuration file, replacing the Hostname value with the virtual server name for your NLB server:

  3. Find UrlRoot. The element is unspecified in the configuration file, but the default value used is a URL in this format: http:// or https://<computername>/<reportserver>, where <reportserver> is the virtual directory name of the Report Server Web service.

  4. Type a value for UrlRoot that includes the virtual name of the cluster in this format: http:// or https://<virtual_server>/<reportserver>.

  5. Save the file.

  6. Repeat these steps in each RSReportServer.config file for each report server in the scale-out deployment.

Verify Report Server Access

Verify that you can access the scale-out deployment through the virtual server name (for example, https://MyVirtualServerName/reportserver and https://MyVirtualServerName/reports).

You can check which node actually processes reports by looking at the report server log files or by checking the RS execution log (the execution log table contains a column called InstanceName that shows which instance processed a particular request). For more information, see Reporting Services Log Files in SQL Server Books Online.

If you cannot connect to the report server, check the NLB to ensure that requests are sent to the report server and view the report server HTTP log to ensure that the server is receiving the requests.

Troubleshooting Failed Requests

If requests do not reach the report server instances, check the RSReportServer.config file to verify that the virtual server name is specified as the host name for the report server URLs:

  1. Open the RSReportServer.config file in a text editor.

  2. Find <Hostname>, <ReportServerUrl>, and <UrlRoot>, and check the host name for each settings. If the value is not the host name you expect, replace it with the correct host name.

If you start the Reporting Services Configuration tool after making these changes, the tool might change the <ReportServerUrl> settings to the default value. Always keep a backup copy of the configuration files in case you need to replace them with the version that contains the settings you want to use.