The Load Balancing Act
I had some fun lately setting up a Reporting Services farm of two SSRS 2008 R2 nodes and a hardware load balancer. We followed the steps in BOL only to find out that the report server will return sporadic empty pages or MAC viewstate validation errors although the machine key was identical on both servers. We fixed the issues by:
- Enabling sticky sessions in the load balancer (not documented).
- Configuring the ReportServerURL setting (BOL says “Do not modify ReportServerUrl”).
Despite what BOL says or doesn’t say, it appears that sticky sessions required with R2 probably due to the AJAX-based ReportViewer. Here is an example configuration that demonstrates the three settings you need to change in the rsreportserver.config:
<UrlRoot>http://atltstssrsibo/reportserver</UrlRoot>
<Hostname>atltstssrsibo</Hostname>
<ReportServerUrl>http://atltstbir02ibo/reportserver</ReportServerUrl>
On each node, set up ReportServerURL to point to the node itself. In this scenario, atltstssrsibo is the load balancer name and atltstbir02ibo is the node server name.
