After you Perform Initial Configuration of the Panorama Virtual Appliance, the available log storage capacity and the options for expanding it depend on the virtual platform (VMware ESXi server or vCloud Air) and mode (Legacy or Panorama mode): see Panorama Models for details.

To expand the log storage capacity on the Panorama virtual appliance, you must add additional logging disks. Expanding the log storage capacity of an existing logging disk is not supported, and Panorama does not recognize the additional storage capacity. For example; if you added a 2TB logging disk, and then expanded that existing logging disk to 4TB, Panorama continues to recognize the logging disk as having 2TB of storage capacity and ignores the additional 2TB of storage capacity.

Before expanding log storage capacity on Panorama, Determine Panorama Log Storage Requirements.