[Pacemaker] Stonith Device APC AP7900

[Rick Cone]

Andrew,

Thanks for the good information.  I am able to make this work.

I setup groups on the 2 AP7900's with Outlet 1 for the first system and
Outlet 2 the second (on each) and gave them the nodes names.  Then, I
created a group for each (with the same node name),and  also and made all
the ports global.

The apcmastersnmp for some reason did not like being used this way
(complained with errors and basically did not work), so I switched to
external/rackpdu with location constraints.  However, I only run the stonith
connected to just one of the AP7900 units (doesn't matter which one).
Because the Outlets are global, whatever happens to one AP7900, the same
will happen to the other.  Pacemaker gets a good return code from the single
stonith and all seems good.

Thanks,

Rick  



-----Original Message-----
From: Andrew Daugherity [mailto:adaugherity at tamu.edu] 
Sent: Wednesday, November 17, 2010 4:01 PM
To: pacemaker at oss.clusterlabs.org
Subject: Re: [Pacemaker] Stonith Device APC AP7900

> Message: 3
> Date: Tue, 16 Nov 2010 11:24:26 +0100
> From: Dejan Muhamedagic <dejanmm at fastmail.fm>
> To: The Pacemaker cluster resource manager
> 	<pacemaker at oss.clusterlabs.org>
> Subject: Re: [Pacemaker] Stonith Device APC AP7900
> Message-ID: <20101116102426.GA22675 at rondo.homenet>
> Content-Type: text/plain; charset=us-ascii
> 
> Hi,
> 
> On Mon, Nov 15, 2010 at 10:41:22AM -0700, Devin Reade wrote:
> > --On Monday, November 15, 2010 08:40:45 AM -0700 Rick Cone
> > <rcone at securepaymentsystems.com> wrote:
> > 
> > > In production I am planning to have 2 separate AP7900 units each
plugged
> > > into 2 different APC UPS units to achieve that.  I would then have the
> > > single node name on each, for each of the 2 PS's on the individual
> > > systems.
> ...
> 
> Right, there's currently no way to do a simultaneous reset on two
> distinct fencing devices.
> 
> > I think that in such a case you'd also have to ensure that your stonith
> > action is poweroff rather than reset, or your node may not actually
> > lose power (although you could mitigate that likelihood by configuring
> > a longer reset time in the PDU).
> 
> Defining more than one stonith resource wouldn't work in this
> case either, because as soon as one of them reports success, the
> node is considered fenced.

There is one possible solution to this -- the APC switched PDUs do
support being configured in multicast groups, and you can configure
groups of outlets together, even spanning several PDUs.  For example you
could say PDU 1, outlet 1 and PDU 2, outlet 3 are known as "webserver1",
and then tell it to "power cycle webserver1".  If it's not already
supported by the stonith agent it shouldn't be too hard to add it --
APC's syntax is actually documented fairly well.

The obvious disclaimer is that I haven't tried this myself.  I do have a
similar setup, but decided it was easier to use the IPMI stonith agent
(external/ipmi) to control my servers.

-- 
Andrew Daugherity <adaugherity at tamu.edu>
Texas A&M University


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