In this series of blog posts we will help you to design, develop and debug the Resource DLL you are developing to give your application high-availability with Windows Server 2008 & 2008 R2 Failover Clustering.
We recommend you start with the other blog post in the series:
During the Startup call you are being provided with the LogEvent function pointer. This is designed for the diagnostics logging, and the messages you log using this method go straight to the cluster log and are interleaved with messages from the other cluster components. You can create or see the log by following the instructions provided in this blog post