From mboxrd@z Thu Jan  1 00:00:00 1970
Message-ID: <43C1EE47.6070402@lanl.gov>
Date: Sun,  8 Jan 2006 22:01:59 -0700
From: Ronald G Minnich <rminnich@lanl.gov>
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To: Fans of the OS Plan 9 from Bell Labs <9fans@cse.psu.edu>
Subject: Re: [9fans] serial reboot boxes
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oh dear, we're going to go into memory lane.

In the 70s, for our 8-bit 6800 systems, we set up so that BRK would 
produce a reset. This was good, since the ASR-33 had a BRK key. Since 
BRK would work fine from ASR-33 -> modem -> modem -> 6800, we had remote 
reset. I will say no more.

On a coupla thousand nodes here, we have these ICE boxes from Linux 
NetworX that are interesting. You telnet in, and they talk to a little 
module in the box over I2C. Said module can assert reset. You tell said 
module to do it, voila, done. It can also assert soft power cycle. And, 
finally, the ICE box can cycle the AC power. Very, very flexible, and 
very, very useful.

Sometimes, you really want to cycle the AC, sometimes the soft power 
supply, sometimes the reset. For doing reset, well, hmm, the ICE box is 
pricey.

But: you can get reed relays from radio shack. Wire the contacts of the 
reed relay across RST. Drive the relay coil from one of 8 parallel ports 
of a PC. Voila, 8 remote resets. I did use these relays once for a 
remote doorbell, and I can tell you that you could even use the remote 
doorbell + reed relay combo for reset ... that would be amusing. Ring 
the doorbell, reset the rack of machines. The doorbells have multiple 
selectable channels. Fun.

If you have more time than money, this will work. We have more money 
than time, so we use ICE and similar stuff.

ron