[Linux-cluster] Problem Running CMAN, GNBD and GFS on RHEL 5.2

Shaker Qawasmi shakerqawasmi at gmail.com
Mon Aug 18 14:21:31 UTC 2008

I have the following setup:
    1 node, runs as GNBD server, it's export GFS (v1) partition, doesn't
mount it localaly.
    2 nodes (node1,node2), import the GFS (v1) partition from gnbd node and
mount it as DocumentRoot for apache.

all the 3 nodes located on a Hosting Company, they have public IPs so i have
ssh login for this servers without NATing or forwarding.., all located in
one Rack with one subnet and one switch connecting them.
this setup was running for about 3 months, but unfortuntally it's now
stopped for unknown resone,
The problem accour by starting the clustering manager (cman service), then i
can not ping/access the gnbd server outside its subnet, becuase almost all
of the packets were droped, although I can ping it from any server on its
subnet without any packet lose. other nodes are accessible without any
problem, also cman_tool status shows all nodes as connected without any
problem (M).

I solved it by preventing INPUT/OUTPUT traffic for the mulitcast address ( from the server using its firewall (iptables) while keeping
the cman service running, it is not the proper solution because this
mulitcast address demand by clustering service to talk with the other
clustering servers, which they are already using the same multicast address
without any problem.

the hosting company say it's switch does not prevent multicasting.

any idea about this problem?

sorry for my english.

my cluster.conf:
<?xml version="1.0"?>
<cluster name="ex-cluster" config_version="6">

<cman expected_votes="1">

<fence_deamon post_join_delay="60">

<clusternode name="gnbd1.example.com" nodeid="1">
                <method name="single">
                        <device name="gnbd" ipaddr="gnbd1.example.com"/>
<clusternode name="node1.example.com" nodeid="2">
                <method name="single">
                        <device name="gnbd" ipaddr="node1.example.com"/>
<clusternode name="node2.example.com" nodeid="3">
                <method name="single">
                        <device name="gnbd" ipaddr="node2.example.com"/>

        <fencedevice name="gnbd" agent="fence_gnbd" servers="
        <clusterfs device="/dev/sdb1" force_unmount="0" fsid="5391"
fstype="gfs" mountpoint="/www/www-data" name="www" options=""/>

Shaker Qawasmi
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