Date: Thu, 10 Jan 2008 17:09:54 -0600 From: Derek Ragona <derek@computinginnovations.com> To: "Derrick Ryalls" <ryallsd@gmail.com> Cc: FreeBSD Questions <freebsd-questions@freebsd.org> Subject: Re: Nut and RAID on FreeBSD 7.0 Message-ID: <6.0.0.22.2.20080110170728.0244cad0@mail.computinginnovations.com> In-Reply-To: <d5eb95fc0801101443l6b4cd69do6d69d5b90cd91702@mail.gmail.co m> References: <d5eb95fc0801091651h1788afd1m256a824e4722906d@mail.gmail.com> <6.0.0.22.2.20080110025841.023a9bb8@mail.computinginnovations.com> <d5eb95fc0801101140w717095dfhed569274c261e4a6@mail.gmail.com> <6.0.0.22.2.20080110155430.023d29d8@mail.computinginnovations.com> <d5eb95fc0801101443l6b4cd69do6d69d5b90cd91702@mail.gmail.com>
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At 04:43 PM 1/10/2008, Derrick Ryalls wrote:
> > >
> > > Greetings,
> > >
> > > I have a RAID fileserver plugged into a UPS and nut is able to
> > > communicate with it successfully. With the winds making the lights
> > > flicker, I started looking into having the computer shut down when
> > > power goes out for more than say 5 minutes or so. Looking at the
> > > documentation, I found that the 'true' solution is more like the
> > > system goes into a safe state when the battery gets low, then the ups
> > > eventually dies. When power is restored, the UPS and computer are
> > > supposed to both come back to life. This would be a great system to
> > > have in place, but it does sound a bit risky and so may not be worth
> > > doing just to save my home fileserver.
> > >
> > > The instructions and the conf file have the shutdown command of
> > > 'shutdown -h +0' which will halt the system. The man page for halt
> > > says the the disk cache will be flushed, but doesn't mention anything
> > > about going to read-only or anything. I suppose my first question is
> > > whether or not flushing the cache is sufficient to save the RAID (5)
> > > array, or if I need to find a way to get the file systems into read
> > > only mode?
> > >
> > > The second question has to do with a rc.d script that nut recommends
> > > creating. The script does a 'upsdrvctl shutdown' and then a sleep
> > > 120, basically waiting for the machine to die while in the script.
> > > Won't this block the other rc.d scripts? Also, is this the magic part
> > > that enables the machine to auto power up when power is restored?
> > >
> > > Changing the shutdown command in nut to 'shutdown -p +0' looks like
> > > the sure fire way to get the system down clean before the power is
> > > lost, but if my concerns are not valid, then I could be missing out on
> > > some nice functionality for no reason.
> > >
> > > Does anyone have experience with this?
> > > I have my servers all using nut to safely shutdown. My
> configuration is
> > > the servers are set up with one as master for nut, that master connected
> > to
> > > the UPS. The other servers are slaves and get their nut information
> from
> > > the master.
> > >
> > > My setup has the servers wait until the UPS is on low battery, then
> they
> > > all shutdown.
> > >
> > > As a separate part of the setup, the servers are set in their BIOS to
> > power
> > > on, after a power failure. This is in the BIOS power setup.
> > >
> > > So if there is a minor power problem, the servers run from battery. In
> > a
> > > larger power outage, they are shutdown cleanly once the battery level is
> > > low, and power up automatically once power is restored.
> > >
> > > In my upsmon.conf file I have this:
> > > SHUTDOWNCMD "/sbin/shutdown -h +0"
> > >
> > > If you want more specifics, I can look through the configuration files
> > and
> > > email you relevant settings.
> > >
> >
> > After doing more reading, I am confident that a shutdown -h would be
> > sufficient, but am a bit concern on the order of operations. The nut
> > documentation has a recommendation to add a kill script as such:
> >
> >
> > #!/bin/sh
> >
> > if [ "$1" == "stop" ]
> > then
> >
> > if [ -f /etc/killpower ]
> > then
> > echo "Killing the power, bye!"
> > /usr/local/libexec/nut/upsdrvctl shutdown
> >
> > sleep 120
> > fi
> > fi
> >
> > </copy>
> >
> > Even if I name this zz_killpower.sh to make it run last, depending on
> > how long it takes FreeBSD to flush the cash after all rc.d scripts are
> > run, I could end up doing a dirty power down, right? Without this, if
> > the power does come back while before the battery finally dies, the
> > system won't restart since the power was never fully interrupted at
> > the computer side?
> > You are reading the old documentation. The current nut, 2.2, has complete
> > rc scripts that are installed in /usr/local/etc/rc.d
> >
> > You need only define the flag file you want to use in upsmon.conf
> >
> > Also define what actions you want in that file as well. You need to use
> > the sample files installed in /usr/local/etc/nut and be sure to read the
> > comments.
> >
>
>I have 2.2 installed and am using the existing scripts. In the
>comments in uspmon.conf, there is this part:
>
># --------------------------------------------------------------------------
># POWERDOWNFLAG - Flag file for forcing UPS shutdown on the master system
>#
># upsmon will create a file with this name in master mode when it's time
># to shut down the load. You should check for this file's existence in
># your shutdown scripts and run 'upsdrvctl shutdown' if it exists.
>#
># See the shutdown.txt file in the docs subdirectory for more information.
>
>POWERDOWNFLAG /etc/killpower
>
>Which in the related documentation means I need the custom shutdown
>script mentioned above which checks for the existence of the
>/etc/killpower file before doing the upsdrvctl shutdown command to
>kill the UPS before the battery is completely dead. I suppose in your
>situation you won't need this extra script as you run until the UPS is
>critical whereas I am trying to kill the system a bit early, before it
>is critical.
>
>Perhaps I need to re-evaluate my line of thinking. Light sometime
>flicker, but power almost never goes out. When it does it is either
>back on in less than 1 minute, or out for hours. If the UPS detects
>critical correctly and gives me at least a minute before death, then
>that should be plenty of time for the system to auto-shutdown. Guess
>I will have to do some experimentation tonight.
Also, the first thing that starts to go bad on a UPS is the
batterylife. So just shutting down on low battery works well. In my case,
I don't worry about the UPS, it is so low on power by then it just chirps
for another minute or so then it dies, completely exhausted.
-Derek
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