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From: jmaynard@thesis1.hsch.utexas.edu (Jay Maynard)
Newsgroups: comp.arch
Subject: Re: Computers for users not programmers
Message-ID: <4702@lib.tmc.edu>
Date: 8 Feb 91 17:13:33 GMT
References: <13252@lanl.gov> <2880@charon.cwi.nl> <1991Feb02.112415.6180@kithrup.COM>
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In article <1991Feb02.112415.6180@kithrup.COM> sef@kithrup.COM (Sean Eric Fagan) writes:
>Unix doesn't have automatic crash recovery, *in general*, because there is
>no standard way to do it.  Note that SysV has a SIGPWR, but I don't think
>anyone actually uses it.  However, it shouldn't be too difficult to hook up
>a UPS to a unix box, and write a driver that gets a signal from the UPS and
>puts a copy of system memory onto disk; all you need to do, then, is add an
>option to the startup sequence to "recover," and, again, you're set.

Actually, the NCR Tower series (at least my XP does this) does use SIGPWR.
It has a battery backing up main memory, and if power is lost, as long as
the battery can keep the memory alive, recovery from an outage is simple:
the power recovery routine reloads any code running in intelligent
peripherals (which aren't battery-backed), performs some miscellaneous
cleanup, and then resumes where execution left off. The first time I knocked
the plug out of the wall at home, I plugged it back in, the machine ran
through its power-up diagnostics, told me it was beginning power fail
recovery, told me it was reloading the serial I/O board, and then apparently
hung. After a while, I got impatient, and hit enter - and was greeted by
the shell prompt, just as though nothing had ever happened.

No, Unix doesn't do power fail recovery, does it?

-- 
Jay Maynard, EMT-P, K5ZC, PP-ASEL | Never ascribe to malice that which can
jmaynard@thesis1.hsch.utexas.edu  | adequately be explained by stupidity.
"Today is different from yesterday." -- State Department spokesman Margaret
Tutwiler, 17 Jan 91, explaining why they won't negotiate with Saddam Hussein