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Thank you for your quick response. First, ideally we do want the
"best connectivity" approach. Assuming each node is connected to the
ping hosts via separate NIC's, switches, cables, etc, a failure in
one of those components will result in one node having degraded
network connectivity. But if that approach is not possible, without
experiencing the spurious fail-overs in tie score situations, then
we may have to settle for the "all or nothing" approach that you
suggest. Second, doesn't your suggested approach have the same race
condition problem if both nodes score drop to zero (e.g.
connectivity lost from both nodes to a single ping host)?<br>
<br>
Regards,<br>
Brad<br>
<br>
On 09/08/2011 02:40 PM, Florian Haas wrote:
<blockquote cite="mid:4E691A20.3040903@gmx.net" type="cite">
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<pre wrap="">On 09/08/11 20:59, Brad Johnson wrote:
</pre>
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<pre wrap="">We have a 2 node cluster with a single resource. The resource must run
on only a single node at one time. Using the pacemaker:ocf:ping RA we
are pinging a WAN gateway and a LAN host on each node so the resource
runs on the node with the greatest connectivity. The problem is when a
ping host goes down (so both nodes lose connectivity to it), the
resource moves to the other node due to timing differences in how fast
they update the score attribute. The dampening value has no effect,
since it delays both nodes by the same amount. These unnecessary
fail-overs aren't acceptable since they are disruptive to the network
for no reason.
Is there a way to dampen the ping update by different amounts on the
active and passive nodes? Or some other way to configure the cluster to
try to keep the resource where it is during these tie score scenarios?
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location pingd-constraint group_1 \
rule $id="pingd-constraint-rule" pingd: defined pingd
May I suggest that you simply change this constraint to
location pingd-constraint group_1 \
rule $id="pingd-constraint-rule" \
-inf: not_defined pingd or pingd lte 0
That way, only a host that definitely has _no_ connectivity carries a
-INF score for that resource group. And I believe that is what you
really want, rather than take the actual ping score as a placement
weight (your "best connectivity" approach).
Just my 2 cents, though.
Cheers,
Florian
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