XenServer 6 introduced the new Integrated Site Recovery (maintained in 7.3), replacing the StorageLink Gateway Site Recovery used in previous versions. It utilizes the native remote data replication between physical storage arrays and automates the recovery and failback capabilities. The new approach removes the Windows VM requirement for the StorageLink Gateway components and it works now with any iSCSI or Hardware HBA storage repository (rather only the restricted storage options with StorageLink support). You can perform failover, failback and test failover. You can configure and operate it using the Disaster Recovery option in XenCenter. Please note however that Site Recovery does NOT interact with the Storage array, so you will have to e.g. manually break mirror relationships before failing over. You will need to ensure that the virtual disks as well as the pool meta data (containing all the configuration data required to recreate your vims and vApps) are correctly replicated to your secondary site.