[Ocfs2-users] I have questions regarding Fencing

[Enrique Sanchez]

As per the message in

http://oss.oracle.com/pipermail/ocfs2-users/2009-November/004019.html

Whenever there is a split brain scenario, the node with the lowest
number survive, I am sold on that and have no argument against it, but
when Node0 crashes, Node1 also takes a nose dive, may I know why?

also, on the FAQ says:

<quote>
QUORUM AND FENCING

What is a quorum?
A quorum is a designation given to a group of nodes in a cluster which
are still allowed to operate on shared storage. It comes up when there
is a failure in the cluster which breaks the nodes up into groups
which can communicate in their groups and with the shared storage but
not between groups.
How does OCFS2's cluster services define a quorum? The quorum decision
is made by a single node based on the number of other nodes that are
considered alive by heartbeating and the number of other nodes that
are reachable via the network.
A node has quorum when:
it sees an odd number of heartbeating nodes and has network
connectivity to more than half of them.
OR,
it sees an even number of heartbeating nodes and has network
connectivity to at least half of them *and* has connectivity to the
heartbeating node with the lowest node number.

</quote>

What is the node with the lowest number? does it have to be Node0? or
does it mean connectivity to the lowest surviving Node?

I setup a test scenario with 4 nodes, 2 nodes mounting the filesystems
and 2 other nodes just participating as network members:

Node0 and Node1 have network connectivity and mount the filesystems
Node3 and Node4 are alive & on the network.

During my test (take Node0 down cold turkey)  Node1 hung pretty badly,
is this something expected??


thanks.
enrique sanchez.





-- 
Enrique Sanchez Vela
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