[Pacemaker] Stonith Device APC AP7900

[Rick Cone]

Devin,

I certainly have the PDU set for poweroff.  I am actually going to be
testing this setup today.  I'll let you know how it goes.  If you have any
further thoughts or investigations (etc.) as to if this will work, let me
know.

Thanks,

Rick

-----Original Message-----
From: Devin Reade [mailto:gdr at gno.org] 
Sent: Monday, November 15, 2010 10:41 AM
To: pacemaker at oss.clusterlabs.org
Subject: Re: [Pacemaker] Stonith Device APC AP7900

--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.)

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).

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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