[3826] in RedHat Linux List
Re: UPS reccomendations
daemon@ATHENA.MIT.EDU (Eric Smith)
Mon Nov 11 02:34:02 1996
Date: 11 Nov 1996 08:19:48 -0000
From: Eric Smith <eric@brouhaha.com>
To: redhat-list@redhat.com
CC: Daniel Senie <dts@senie.com>, David Myers <dem@skyline.rtp.nc.us>,
Pavel Korensky <pavelk@dator3.anet.cz>
In-reply-to: <Pine.LNX.3.95.961110231628.14900C-100000@peanut.senie.com>
(message from Daniel Senie on Sun, 10 Nov 1996 23:24:04 -0500 (EST))
Resent-From: redhat-list@redhat.com
Reply-To: redhat-list@redhat.com
David Myers <dem@skyline.rtp.nc.us> wrote about the "apcd" program for Linux
to talk to the APC SmartUPS:
> Someone made an RPM, but I caution those who install it that it
> doesn't shut down your system properly. It contains a hard-coded
> sequence of commands to halt the OS, rather than signalling the init
> process to carry out an orderly shutdown. Not a good idea.
And Daniel Senie <dts@senie.com> wrote:
> Perhaps it's not a good idea, but I think there's a reason. First, the
> code that's there is lifted from the shutdown code in the kernel (an older
> kernel at this point).
>
> Now for the reason to have custom shutdown... it's necessary for the
> program doing the shutdown to get off one final command to the UPS to tell
> the UPS that it's OK to cut power to the system. Somehow that has to be
> sent out. If that command can be sent while still using the standard
> shutdown, then that would indeed be preferable.
There are in fact several possible ways to do that, including the "K" command
(delayed UPS shutdown) which the author of apcd,
Pavel Korensky <pavelk@dator3.anet.cz> seems not to have been aware of.
However, even the "Z" command (immediate UPS shutdown) could be used if it
was sent from the appropriate place in a script. For instance,
near the end of /etc/rc.d/init.d/halt, after the file systems have been
unmounted. Pavel probably didn't want to do this because it would likely
require different script changes for different Linux distributions. As a
certifiable Red Hat Linux bigot, I really don't care about that.
Cheers,
Eric
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