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  • From: Sil Greene <Sil_Greene AT unc.edu>
  • To: internetworkers AT lists.ibiblio.org
  • Subject: Re: [internetworkers] 15 seconds of what
  • Date: Fri, 23 Aug 2002 14:37:06 -0400

Two words: power cycling. Basically, you wait long enough for
capacitors to drain, which allows you to bring the system back online in
a known state. (This is a "cold boot"; an immediate restart without
waiting long enough is a "warm boot".) I think the "proper" amount of
time is closer to 30 seconds, but I'm sure it varies with the device.

I've found power cycling necessary when resetting semi-intelligent
networking devices (switches, DSL/cable routers or modems, etc).


From the jargon file:

power cycle (vt.)

(also, `cycle power' or just `cycle') To power off a machine and then
power it on immediately, with the intention of clearing some kind of
hung or gronked state. Syn. 120 reset; see also Big Red Switch. Compare
Vulcan nerve pinch, bounce (sense 4), and boot, and see the "Some AI
Koans" (in Appendix A) about Tom Knight and the novice.


The AI Koan about Tom Knight:

A novice was trying to fix a broken Lisp machine by turning the power
off and on.

Knight, seeing what the student was doing, spoke sternly: "You cannot
fix a machine by just power-cycling it with no understanding of what is
going wrong."

Knight turned the machine off and on.

The machine worked.


(I've found this to be quite true -- often I can fix a problem machine
just by power cycling it while the machine's owner swears up and down
they've already tried that 20 times...)

Hope that helps,
--sil

machett AT ibiblio.org wrote:
>
> This is a completely inane question, but it has positively consumed my
> curiosity.
>
> One of the computers where I work has a penchant for crashing so hard that
> not even Ctrl-Alt-Del works. Now, at such times when hitting the power
> button becomes necessary, I've caught myself counting 15 seconds before
> restoring power. Finding this to be an odd sort of thing to do, I took
> some time to wonder why I did it in the first place. I vaguely recall from
> my youthful days of textured monitors with green screens that, when
> resetting a system, one should wait 15s. for ... and this is where my vague
> memory fails me.
>
> Is my memory faulty or was there indeed some valid reason back in the day
> for waiting 15s. before restoring power to a computer?
>
> -Alan

--
"If you put your supper dish to your ears you can hear the sounds
of a restaurant." --Snoopy (Charles Schultz 02-12-2000 RIP)
Sil_Greene AT unc.edu *&* Do not taunt Happy Fun Sil




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