Last week I got the chance to work on an Active, Active, Active SQL Server 2008 Cluster install. This was new to me and very fun. We have three physical hosts all using SQL Server 2008 Enterprise Edition. The Servers are also running Windows Server 2008 Enterprise Edition. I worked with one of our windows admins to do the install. First the windows admin set up the windows cluster and assigned all of the storage to the cluster but did not assign it to an application or service. Once that was done we had to set up the Distributed Transaction Coordinator and give it its storage. Now we started the install of SQL Server 2008. Since all of the storage was owned by one server we installed all three instances, one for each node, of SQL Server on that server and that created the different cluster applications for us. Then on each of the other servers we added a node three times, again once for each instance. Now that is complete we can fail over the resources for any instance to any of the physical nodes. Very cool.