The button Start Disaster Recovery only appears if your license includes One Button Disaster Recovery.
This button starts an automatical disaster recovery given that there is a medium with a self-backup in drive 1. After pressing this button a window with a security question (Should a disaster recovery be launched?) is opened. Next, the drive is checked and the label and the savesetsof the medium are shown. After clicking the 'OK' button the disaster recovery is launched. At this point the self-backup of the SEP sesam server is searched and, if found, restored back to its source in overwrite mode.