Rick Stevens wrote:
Jakov Sosic wrote:
On Mon, 31 Aug 2009 15:30:13 -0500
Alan A <alan.zg@xxxxxxxxx> wrote:
You have to give your cluster 2 node setting on remaining two nodes.
How can I define a two-node cluster if a majority is needed to reach
quorum?
We had to allow two-node clusters, so we made a special exception to
the quorum rules. There is a special setting "two_node" in
the /etc/cluster.conf file that looks like this:
<cman expected_votes="1" two_node="1"/>
This will allow one node to be considered enough to establish a
quorum. Note that if you configure a quorum disk/partition, you don't
want two_node="1".
http://sources.redhat.com/cluster/wiki/FAQ/CMAN#two_node
Yeah I know how to set up two_node cluster, but didn't know that
reconfiguration is the only way out when one node is missing :( I'm
disappointed with this limitation, I hope that developers will sort it
out for RHEL6 :(
I don't see that there's anything to fix. You had a three-node cluster
so you needed a majority of nodes up to maintain a quorum. One node
died, killing quorum and thus stopping the cluster (the expected and
correct behavior). As a three-node cluster, it's dead. It can't be run
as a three-node cluster until the third node is fixed. Those are the
rules.
A two node cluster requires special handling of things to prevent the
dread split-brain situation, which is what two_node does. Running the
surviving nodes as a two-node cluster is, by definition, a
reconfiguration. I'd say simply requiring you to set two_node is pretty
damned innocuous to let you run a dead (ok, mortally wounded) cluster.
If you pulled a drive out of a RAID6--thus degrading it to a RAID5--
would you complain because it didn't remain a RAID6?
On re-reading my response, it seemed unintentionally harsh. I didn't
mean any disrespect, sir. I was simply questioning the concept that a
reconfiguration of a cluster shouldn't be required when, indeed the
cluster was being reconfigured. The other response I saw to this
thread regarding planning, and things such as last-man-standing was much
better worded.
My apologies if it seemed I was jumping down your throat. I wasn't.
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