[Pacemaker] Stonith Device APC AP7900

[Rick Cone]

Dejan,

Well, I will got back to plan B and use the power splitter.

Thanks,

Rick

-----Original Message-----
From: Dejan Muhamedagic [mailto:dejanmm at fastmail.fm] 
Sent: Tuesday, November 16, 2010 3:24 AM
To: The Pacemaker cluster resource manager
Subject: Re: [Pacemaker] Stonith Device APC AP7900

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.
> 
> So for this setup, you would have to trigger two stonith devices, one
> for each AP7900, with identical node names.  Only after both succeeded
> would you be able to consider the node to be dead.  Correct?
> 
> I don't recall reading anything in the pacemaker et al documentation that
> would cover this case.  I was under the impression that after one 
> stonith resource is successfully invoked, the node would be considered
> to be offline.  If so, I'd be suspicious about assuming both PDUs
> would get activated without further investigation and testing.  (I 
> don't think that you could consider two node names on one PDU to be
> equivalent to one on each of two PDUs.)

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.

Thanks,

Dejan

> However, while I've written RAs before, I've never looked at the stonith
> logic, so I could be completely out to lunch.  It sounds like an
interesting
> edge case, and edge cases make me nervous :)
> 
> Devin
> 
> 
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