Xref: utzoo comp.sys.att:2084 comp.unix.wizards:6095
Path: utzoo!utgpu!water!watmath!clyde!burl!codas!mtune!whuts!picuxa!tgr
From: tgr@picuxa.UUCP (Dr. Emilio Lizardo)
Newsgroups: comp.sys.att,comp.unix.wizards
Subject: Re: Big fun with unix ports
Summary: What happens when the machine goes down?
Keywords: 3B2, AIC
Message-ID: <448@picuxa.UUCP>
Date: 14 Jan 88 14:39:21 GMT
References: <301@paisano.UUCP> <118@mybest.UUCP> <53@richp1.UUCP>
Reply-To: tgr@picuxa.UUCP (Dr. Emilio Lizardo)
Organization: Trenton Home for the Criminally Insane
Lines: 31


In all of this discussion about using one machine (3B, PC or whatever)
to monitor the console ports of multiple 3Bs, I see something missing:
the problem of a remoted console when the machine being monitored goes
down.  When a 3B2 boots/shuts down (possibly for any change of init state,
but I'm not sure of that), the console port *deliberately* drops DTR.
This is to ensure that you have a locally attached console terminal, not
a modem (which will hang up the call when it perceives loss of DTR).

A 3B2 ports card will also drop the connection unless you do something with
the stty, so just hooking up a 630 to a 3B2 to monitor other 3B2s will not
work; some effort will be involved.

If $$ are available, I suggest the original poster look into buying
the 3B2 Remote Management Package, which includes an Alarm Interface Card
(AIC).  This board provides the capability to remotely access the console
port of any 3B by trapping loss of DTR.  Additional features include the
ability to monitor the 3B for panics/crashes with other computer alarm
devices available from assorted vendors, "panic auto-reboot" capability,
and support for UPS.  Use an alarm device (the one I've seen used is
called "Silent Knight" but that's not to be construed as a recommendation)
to monitor the machines for crashes, and use a single terminal with a
ABC switch to connect to the AIC console ports from a single terminal.
Not only will you be able to monitor multiple 3Bs, but your monitoring
capability will not be hampered when one of the machines crashes.

-- 
Tom Gillespie  ( ...ihnp4!picuxa!tgr) | (attmail!tgillespie) (201) 952-1178
AT&T/EDS Product Integration Center  299 Jefferson Rd. Parsippany NJ 07054

"Don't take life so serious ... it ain't nohow permanent."  -- Walt Kelly