HP A3550A - High Availability Disk Arrays Model 20 Storage Enclosure User Manual page 126

Note If configuring the disk array using a direct-connect terminal, it is also possible to
complete any RAID configuration modifications before attaching the disk array to the
host computer. If terminal emulation is used, the disk array will come up in the factory-
default configuration of RAID-5 LUNs.
Terminal Emulation through a MUX on the Host
Note MUX support is not available over the Fibre Channel links because of RS-232C
distance limitations. Configuration of disk arrays on Fibre Channel links more than 50
feet from a MUX panel must be done using SAM or STM.
3-14 Make the RS-232C Connection to the Host System