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标题
Multiple Report Servers, is it a supported scenario? -
说明
Need to install two report servers pointing to the same database, for availability purposes. Is this a supported scenario? -
原因
Need to know if there are any potential problems in this scenario. -
解决办法
Having two or more Enterprise Reporter servers using the same database and running at the same time is not a supported scenario, and will, sooner or later, result in conflicts within the server(s):
1. The nodes can only connect to a single server at a time, so if they are connected to Server1, they are not connected to Server2. When nodes are connected to a server, they periodically send a "heartbeat" packet to give the server information about the health of the node. When a certain number of heartbeats have been missed, the server marks those nodes as "faulted" which is an internal state that basically means, "don't send any more work to this node until we receive a heartbeat from that node". Since the nodes are connected to Server1, Server2 will have marked all nodes as faulted.
2. On startup, the server builds an internal model of the clusters, nodes and tasks that are assigned to each node. The internal model is updated by state changes communicated from the nodes to the server. Since Server1 has connected nodes, its internal model will be updated. Server2, on the other hand, is not receiving such update notifications, so its internal model will never change.
3. On startup, the nodes read a configuration file telling them which server to which they should connect. There is no mechanism built in the nodes to tell them to switch to another server in the event the server they were connected to can not be found.
4. Even leaving the server turned off would require significant work. The major issue is the fact that you would need to use the same set of clusters and nodes (this information is persisted in the database so Server1 will read the same node information as Server2 on startup). This would require shutting down each node, individually modifying both the configuration file (ReporterNode.exe.config) and updating a database entry that contains node configuration information to point to Server2 and restarting the node services. Finally, you would need to start Server2.
Hence, using multiple ER servers is not recommended or supported.