SQL Server: multiple failover cluster instances with disjoint storage This is for SQL Server 2012. I currently have two datacenters that have separate SANs. I'm using failover cluster instances (FCIs) for server redundancy, and then AlwaysOn Availability Groups (AGs) for datacenter redundancy. This is what it looks like:



The problem is that I'd like FCIs at both datacenters, like so:



When we try to add the storage for Nodes3&amp;4 we can't because the storage is not shared with Nodes1&amp;2. At Add Storage to a Failover Cluster it says:

The disk must be available to all nodes in the cluster before you can add it to the set of storage for the cluster.

It is my understanding that Nodes1,2,3,4 must all be in the same Windows Failover Cluster in order to use AGs. However, this requirement seems to prevent us from being able to setup FCIs in both datacenters. 

Is there any way to have my cake and eat it to?
I've found the answer to this problem. It is possible, but you either need Windows 2008R2 SP1 or higher, or a hotfix. The full details are at:

AlwaysOn Architecture Guide: Building a High Availability and Disaster Recovery Solution by Using Failover Cluster Instances and Availability Groups

To quote a line from this article: This arrangement of storage, where a cluster disk is shared between a subset of nodes within a WSFC, is referred to as asymmetric storage