cman(5)cman(5)NAMEcman ‐ cluster.conf cman configuration section
DESCRIPTION
Cman configuration values are placed in the <cman> </cman>
section of cluster.conf. Per‐node configuration related
to cman is placed in the standard <clusternode> </clus‐
ternode> sections. All cman configuration settings are
optional; usually none are used. The <cman> section is
placed under the <cluster> section in cluster.conf.
<cluster>
<cman>
</cman>
...
</cluster>
UDP port
By default, cman will use UDP port 5405/5404 for internode
communication. This can be changed by setting a port num‐
ber as follows:
<cman port="6809">
</cman>
This will cause cman to use ports 6809 and 6808 for clus‐
ter communications.
Expected votes
The expected votes value is used by cman to determine quo‐
rum. The cluster is quorate if the sum of votes of exist‐
ing members is over half of the expected votes value. By
default, cman sets the expected votes value to be the sum
of votes of all nodes listed in cluster.conf. This can be
overriden by setting an explicit expected_votes value as
follows:
<cman expected_votes="3">
</cman>
If the cluster becomes partitioned, improper use of this
option can result in more than one partition gaining quo‐
rum. In that event, nodes in each partition will enable
cluster services.
Two node clusters
Ordinarily, the loss of quorum after one out of two nodes
fails will prevent the remaining node from continuing (if
both nodes have one vote.) Special configuration options
can be set to allow the one remaining node to continue op‐
erating if the other fails. To do this only two nodes,
each with one vote, can be defined in cluster.conf. The
two_node and expected_votes values must then be set to 1
in the cman section as follows.
<cman two_node="1" expected_votes="1">
</cman>
Node votes
By default, a node is given one vote toward the calcula‐
tion of quorum. This can be changed by giving a node a
specific number of votes as follows:
<clusternode name="nd1" votes="2">
</clusternode>
Node ID
All nodes must have a unique node ID. This is a single in‐
teger that identifies it to the cluster. A node’s appli‐
cation to join the cluster may be rejected if you try to
set the nodeid to one that is already used.
<clusternode name="nd1" nodeid="1">
</clusternode>
Multicast network configurationcman uses multicast UDP packets to communicate with other
nodes in the cluster. By default it will generate a mul‐
ticast address using 239.192.x.x where x.x is the 16bit
cluster ID number split into bytes. This, in turn is gen‐
erated from a hash of the cluster name though it can be
specified explicitly. The purpose of this is to allow mul‐
tiple clusters to share the same subnet ‐ they will each
use a different multicast address. You might also/instead
want to isolate clusters using the port number as shown
above.
It is possible to override the multicast address by speci‐
fying it in cluster.conf as shown:
<cman>
<multicast addr="229.192.0.1"/>
</cman>
Cluster ID
The cluster ID number is used to isolate clusters in the
same subnet. Usually it is generated from a hash of the
cluster name, but it can be overridden here if you feel
the need. Sometimes cluster names can hash to the same ID.
<cman cluster_id="669">
</cman>
openais security key
All traffic sent out by cman/openais is encrypted. By de‐
fault the security key used is simply the cluster name. If
you need more security you can specify a key file that
contains the key used to encrypt cluster communications.
Of course, the contents of the key file must be the same
on all nodes in the cluster. It is up to you to securely
copy the file to the nodes.
<cman keyfile="/etc/openais.key">
</cman>
Note that this only applies to cluster communication. The
DLM does not encrypt traffic.
Other openais parameters
When openais is started by cman (cman_tool runs aisexec),
the openais.conf file is not used. Many of the configura‐
tion parameters listed in openais.conf can be set in clus‐
ter.conf (CCS) instead. Cman will read openais parameters
from the following sections in cluster.conf and load them
into openais:
<cluster>
<totem />
<logging />
<event />
<aisexec />
<group />
</cluster>
See the man page for more information on keys that are
valid for these sections. Note that settings in the
<clusternodes> section will override settings in the sec‐
tions above, and options on the cman_tool command line
will override both. In particular, settings like bindne‐
taddr, mcastaddr, mcastport and nodeid will always be re‐
placed by values in <clusternodes>.
Cman uses different defaults for some of the openais pa‐
rameters listed in openais.conf(5). If you wish to use a
non‐default setting, they can be configured in clus‐
ter.conf as shown above. Cman uses the following default
values:
<totem
vsftype="none"
token="10000"
token_retransmits_before_loss_const="20"
join="60"
consensus="4800"
rrp_mode="none"
<!‐‐ or rrp_mode="active" if altnames are present >
/>
<logging syslog_facility="local4" />
<aisexec user="root" group="root" />
Here’s how to set the token timeout to five seconds:
<totem token="5000"/>
And this is how to add extra openais logging options to
CMAN and CPG:
<logging to_stderr="yes">
<logger ident="CPG" debug="on" to_stderr="yes">
</logger>
<logger ident="CMAN" debug="on" to_stderr="yes">
</logger>
</logging>
SEE ALSOcluster.conf(5), openais.conf(5), ccs(7), cman_tool(8)
