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Ask Slashdot: Hardware for Headless Linux Boxes
Alan Hodgkinson asks:
"I would like to setup a bunch of Linux boxes without
keyboards and monitors. The systems must be
accessable/controlable via their serial ports, including
the ability to send them a hard reset. Sun Sparc hardware
has this feature. You can remove the keyboard and the
system will boot and send all its console output through
the serial port. You can even reset the machine by sending
a break to the serial port. Is there any hardware available
for PCs that will provides this functionality? (And that
works on a wide variety of PC hardware). ISPs must face
this problem. What do they do? Tips anyone?"
Ok, so we're the poor bastards who came up with this and are building it. As some of you were able to figure out, that's a PS/2 keyboard port on the back of the board meant to jumper to the PC keyboard port..
So what started as a couple of guys needing a decent way to manage cheap fast hardware in their webservers, seems to have turned into a small tornado of interest... I don't know who told who and how it got to slashdot. We were hoping to keep a lid on this until it was finished....
Present status is that it's basically functional but has some rough edges and needs some 'usability' help... The coding and design has been taking a back seat to 'real work' because there are bills to pay... This is sadly still the case so try not to lean on us too hard please..
Herb.
http://www.realweasel.com/ A dumb name for a dumb answer to a really dumb question.
You should compile your kernel with support for a /etc/inittab to run a getty on the tty line. You should also modify your lilo.conf to enable the console on a serial line.
/usr/src/linux/drivers/char/serial.c. The current code will generate a SIGINT signal to the foreground process group if a break is sent. (If the BRKINT termios option is enabled, and IGNBRK is not enabled). There is also support for the break signal to act as the SAK (secure attention key). It shouldn't be too hard to force a reboot if a break is received. I don't think that you can reboot the machine from within an interrupt context, but you could wake up a ``watchdog'' process which will do the reboot. Add an ioctl() which causes the calling process to block indefinitely. When a break is received, wake up the process. Then write a userland process that opens the tty, calls the ioctl and then reboots the machine if the ioctl returns with a successful error code. This is largely trivial to write, since the code for handling break is already there.
/sbin/shutdown:
/dev/ttyS0 ; then
/sbin/shutdown -r now
serial console. Then add a getty line to your
I was playing with this a few days ago, but my
old terminal blew up on me!
Also, if you want to reset the machine by sending break, you have to do a little kernel modification in
The ioctl could be wrapped up in a tiny tool which is then used in a shell script that runs
if shutdown_watcher
fi
Of course, if the machine is too hosed to reboot, this obviously won't work. A hardware solution is required that turns the break signal into a hard reset.
I admin servers in New Jersey and San Francisco. I am in Ohio. We have a portmaster 2 terminal server on the net we can telnet to, then get a serial based login prompt to the machines. The suns talk to the serial from the very beginning. You can get what equates to the BIOS setup screen over the serial. No octopus monitor switch does that for you. And no monitor switch helps you if you're in Ohio and the machine is in New Jersey. New Intel Dual PII/III boards have a bios feature that puts the info out a serial, just like the suns. This may be the Phoenix Bios that others have talked about. A friend has several of these. over a serial connection, the machine boots and you can enter the bios screen. You can get a lilo prompt. That's the kind of control you need over remote machines.
The best solution we ever found was -
1) recompile linux (2.1+) kernel to 'use serial port as console' which means if you boot sans video card you get a serial console.
2) set mobo for 'ignore errors on boot'
3) use an APC powerstrip with serial and telnet access to powering on/off outlets individually
4) use a portmaster connected to all the serial ports and the APC.
dialback only modem access into the portmaster as well as network access
Most of the sites we set up were colo sites, or in locked secure server rooms so remote access was a boon.
Any questions?
"No good deed goes unpunished"
First thing, to be able to boot whithout a graphicsadapter you will need a PC with an Award BIOS. The Award BIOS has a seting _NO_VIDEO_INSTALLED_ .
Second you will have to compile a 2.2 kernel with (or FreeBSD) with serialconsole option. To be able to login via your serialconsole you must also modify your inittab to run a getty on that console.
Now comes the tricky parts. To be able to send an hard reset you will need special hardware, thats not good. An alternative solution would use some type of watchdog software. The basic function of a watchdog is to perform a softreset if the machine hangs (simplified that is).
the next problem is what to do with all the serial cables? I hav no idea! Maybe there are some type of hub...
Wonder when my grammar will improve?
Note that there is also remote keyboard/mouse/video boxes that support very long cable lengths, and some that even bridge to a network, essentially acting as hardware remote control.
Given that you can get a switcher pretty cheap nowdays, this might be a better solution than RS232.
--
Business. Numbers. Money. People. Computer World.
Actualy, I thought Compaq and HP servers already had this special hardware built-in. Usually it's used over a network, but some Compaq server allow you to access "managablity" through RS232.
--
Business. Numbers. Money. People. Computer World.
Sounds like you want one of these. They're not on the market yet, though, but they look super-cool.
The long-awaited NetWinder RM (the rackmount version of the NetWinder) is now shipping!
I wish this subject had come up earlier. We recently threw away about 20 old dumb terminals of the Wyse flavor. For some reason our systems software supplier decided that instead of using a terminal to telnet to the host, we needed Windows and Visual Basic to do the same thing. We actually still have some terminals lying around though. Email me if you're interested.
I think some people might be getting a touch confused here, so I'll try and restate the need.
Basically with a Sun machine, you can attach a console to the back and watch the boot process, right from the point where the PROM detects no keyboard present and redirects the console to the serial line. It doesn't matter whether or not you have a video card present for the machine to boot.
On a PC, depending on the BIOS you can or can't get away without a keyboard being present. However none (with the exception of the one I'm going to mention) will let you boot without a video card present. If the card is there then that is what will be your console.
Now people were talking about using the SERIAL CONSOLE directive, or just running getty on the serial line, to redirect it and thats fine, provided the machine boots that far. With a Sun, if it fails to boot because of a problem with the hardware, or misconfiguration in the PROM (BIOS equivalent) you still have console access. On a PC you don't.
Now Phoenix have just brought out a new BIOS which will let you redirect the console to a serial line in the same way as a Sun does, i.e. you can get to the BIOS from the serial line, edit parameters and force a powercycle. This is an immensely cool idea. In the ISP I worked in (one of the largest in Europe) we used vast amounts of PC based UNIX machines (OpenBSD, NetBSD and FreeBSD) none of which we could do this with.
Check out http://www.phoenix.com/platform/ser verbios.html and scroll down to the bit about Serial Remote Console.
HTH HAND
Joe
--
Don't some Ethernet Cards let you boot up remotely? this would solve a lot of problems I think... get an ATX case that can turn itself off through software, then boot of the ethernet... no need for serial cables ether :)
---------------
Chad Okere
ReadThe ReflectionEngine, a cyberpunk style n
There are solutions like http://www.auroratech.com which allow you to control multiple devices (either 16 or 128) from a single console running serial cables out to all the headless machinery. They aren't the only ones out there. Also, I don't know that they would work on any Linux/xBSD or other free platforms. I do know they support Sun/Solaris and NT.
BTW, I don't work for them. I am currently preparing to eval one of their products. They were very willing to send a demo of the hardware and software. Also, they aren't cheap but aren't outrageous.
Do really dense people warp space more than others?
yep - i have two ibm mail servers running linux with just two cords coming out the back...power and network. the ibm bios allows you to set it to keyboardless use, and i just run it w/o monitor and keyboard. however, since they are mail servers (and they ARE running linux) i never need to reboot them - these two have been up for six months or so. so, if for some reason you have need to reboot your headless box frequently, there might be some issues with that.
I got more rhymes than Jamaica got Mangoes.
Try E-bay: I've gotten a few good deals there and haven't been burned once.
John
"Classic UFO's
It may be expensive, but this is the device you want. It allows remote telnet-to-serial control, plus power control (on/off/cycle), and you can also connect from any serial port to any other serial port... If your network's down, just dial up to the modem you connected. ;)
There are a couple of companies that provide these products; Westeren Telematic and Baytech.
This works best if you are using it to manage several computers, because there is a minimum of 8 serial ports.
I tried to submit this URL to slashdot, but
no one saw fit to post it:
www.realweasel.com
I haven't read the whole thread but here's a link to a fully configurable LCD terminal for linIx.
LCDproc is a small program that extracts various statistics about your
machine and displays them on an LCD display. It currently only
supports 20x4 character displays, made by Matrix Orbital Corporation
(a bunch of really cool people). Hit their web site at
http://www.matrix-orbital.com/ for pricing and ordering
information. We'll be supporting more displays in future versions.
http://lcdproc.omnipotent.net/
Surgeon, ze nezherlandz
(No prescription needed)
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