Project Hydra: the USB Multiheaded Monster (servidor de consoles serie)
Reading time: 3 – 4 minutes
Si igual que molts de nosaltres ús veieu obligats a mantenir diversos
servidors Linux/Unix és obvi que usareu algo com un KVM (Keyboard Video
Mouse) switch, per tal de poder anar canviant de consola en cas de ser
necessari, o en el seu defecte des d’una sola consola usareu eines de
gestió remota com el Telnet o l’SSH.
Però si sou de la vella escola com jo, recordareu que hi ha una cosa
que es diuen terminals serie, de fet, fa molt de temps un ex-company del
institut em va comentar (Jordi Just/Noctropolis) em va comentar que estava
montant un servidor de consoles serie per tal de poder administrar els
servidors de forma més eficient sense haver d’anar a la sala de
servidors o de forma remota, només atacant un sól ordinador.
Doncs tot llegint la Linux World, vaig trobar aquest article: Project Hydra: the USB
Multiheaded Monster (local) que
planteja com montar un servidor de consoles serie, però encomptes d’usar
els RS232 de tota la vida, usant el port USB, que a part de ser més
ràpid és l’únic que porten els servidors nous.
Segons el propi article el que plateja és el següent:
It would be really cool to have a dedicated, remotely accessible console
server with a lot of serial ports connected to all of our servers. One way to
do this would be to use multiport serial cards, but they are comparable in
price to serial console switches and have a similar scalability problem.
Instead, we figured out how to use the readily available USB bus with
USB-to-serial adapters. This solution works well even in our mixed environment,
and it is also scalable and inexpensive.
Si el que busqueu és una solució més professional que
el ‘do yourself’ podeu mirar la referència que porta l’article, que esta
molt guapa. Ja que ens permet fer resetes, entrar a la BIOS, etc. tot en
remot… realment molt molt útil. La solució comenrcial en
qüestió: PC Weasel 2000.
Segons la seva propia pàgina web, per tal de solucionar el tema el que
han fet és:
The PC Weasel provides the answer by emulating a video board and
keyboard and presenting a serial port to the outside world. Plugged into an
available ISA or PCI slot, it takes the characters written by your CPU into its
“video” memory and pumps them out its onboard RS-232 port. Characters input by
you into the RS-232 port are converted into keyboard scan codes and presented
to the motherboard’s keyboard connector.
Whether you’re using a dumb terminal next to your computer, dialing in via a
modem connected to the PC Weasel’s serial port, or on the other side of the
world, connecting through an (async) terminal server, your machine will think
it has a local keyboard and monitor.
The PC Weasel also contains an appropriately configurable 16550 UART, which
provides your OS with its normal serial console port after boot. The PC
Weasel’s onboard CPU detects the initialization of this port at bootup and
optionally switches the serial connector over to it, taking the video emulation
offline. The PC Weasel’s CPU then continues to eavesdrop on the console port,
and can be brought online again with a user-programmable escape sequence.