Hi, What is the distance between the 2 sites and is it a Gigabit link or higher? The vSphere storage appliance I believe needs to be in a 3 node configuration at minimum. either 3 nodes mirrored or 2 nodes mirrored with a 3rd acting as Quorum. This may have changed but I expect one of the VMware team will correct me if this is incorrect or has changed.
You may want to take a look at SvSAN from StorMagic, as long as there is a Gigabit link between sites then it will fit your requirements. What version of Vsphere are you running at the sites?