The xsanctl command provides the most direct method for accessing Xsan filesystem functionality from the Terminal:
Use macOS Disk Utility or the diskutil list command to verify that the Mac physically sees the external LUNs. If the LUNs are missing, check the Fibre Channel cables, switches, or host bus adapter (HBA) drivers.
Do not try this on macOS Sequoia. Keep a dedicated Mojave or Catalina machine.