We need to admit this is one of the thing we didn’t pay enough attention in the previous versions of BizTalk 360. Until last week when one of our potential clients raised the issue and told us its a show stopper. We reacted quickly and can confirm from version 1.0.206 and above all the issues related to clustered host instances are fixed.
In majority of the cases you don’t need to cluster the BizTalk host instances. BizTalk group concept having multiple BizTalk servers and the internal mechanism of circulating the load is sufficient to make the host highly available. All you need to do is, create the host instances in multiple servers. But there are certain adapter which are not capable of running in multiple servers, example FTP, POP3 etc. due to the nature of these adapters. In those case you need to configure the host instances running these adapter using Windows clustering.
The first challenge to fix this issue was to setup the environment, our fail over cluster configuration looks as shown below.
Fix 1: Host Instance will have an icon to represent their clustered status
It’s important to differentiate the normal host instance from the clustered ones. So, we introduce small icons in the grid showing they are clustered host instance.
Fix 2: Dashboards reflect the status correctly
In the previous versions (without proper cluster instance handling) the above screen would have shown RED for host instances, since there is host instance in stopped state (refer to previous image). But now the dashboard will show the correct status GREEN understanding the host instances and their cluster behaviour.
Fix 3: Starting/Stopping clustered host instance
Starting and stopping of clustered host instances behaves differently to normal ones. In a normal situation you should be able to start and stop host instances individually without any dependency. But for a clustered host instance case, there is a patter.
1. You can stop the clustered host instance without any issue
2. Starting a host instance will bring the cluster group online rather than starting the host instance standalone.
3. If you try to start the host instance on a failover server (passive server), the behaviour will be same, it will bring the cluster group online rather than trying to start the wrong host instance.
If you want to start the host instance on a passive server, you need to do it via the "Failover Cluster Manager".