They are the least expensive Fibre Channel connectivity device, but they
provide limited management functionality and can support relatively few
devices.
Although Fibre Channel devices can be physically cabled in a loop to
create an arbitrated loop topology, one of the main advantages of a hub
is its ability to automatically bypass a port. In a physical loop, a broken
connection would take the entire loop offline.
Disk drives always support arbitrated loop because a disk drive only
ever wants to be spoken to by one device at a time.
Arbitrated Loop was originally developed as an alternative to Parallel
SCSI.