“Serial consoles do not appear to have much going for them. They
are slow, require special null-modem cables, and do not provide a
graphical interface. But what is going for them is considerable.
Serial cables are standard equipment and can run over RJ-45 cables,
can run up to 200 ft (about 100m) at 9600bps. Serial concentrators
can run the consoles of over 32 ports into a central box, so all
the consoles in a cluster can be accessed from a single
location.”
“You will not require a crash cart, KVM switch, or keyboard,
montior, or mouse. Because of the serial concentrator, you can
access the console of a machine in a colocation cage from your
desktop.”
“The real limiting factor so far has been that even though you
can access the Linux console via a serial port, most x86 hardware
was not set to send its POST and BIOS information to the serial
port. More and more “server” motherboards are starting to include
full serial support in the BIOS, so you can access the BIOS and
make boot changes via the serial port.”