Here is an excellent white paper on SQL Server Multisite Clusters, however they forget to mention that you can also do this with host based replication. Instead, they assume you have “two EMC Symmetrix VMAX enterprise storage arrays, one at each site. The arrays were both configured with two VMAX storage engines and 240 disk drives”. If you have a million plus dollars in your budget for storage, go ahead and knock yourself out. If not, you may want to look into some Fusion-io PCIe Flash storage and host based replication with DataKeeper cluster edition, faster than a SAN at a fraction of the cost with all the availability. Check out how Polaris Industries did just this http://www.fusionio.com/blog/polaris-sios/