cman(5)                                               cluster.conf cman configuration section                                              cman(5)

NAME

       cman - 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> </clusternode> 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 number as follows:

                <cman port="6809">
                </cman>

              This will cause cman to use ports 6809 and 6808 for cluster communications.

       Expected votes
              The  expected  votes  value  is used by cman to determine quorum.  The cluster is quorate if the sum of votes of existing 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 overridden 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 quorum.  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 operating 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 calculation 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 integer that identifies it to the cluster.  A node's application 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>

       Multi-home configuration
              It  is quite common to use multiple ethernet adapters for cluster nodes, so they will tolerate the failure of one link. A common way
              to do this is to use ethernet bonding. Alternatively you can get corosync to run in redundant ring mode by specifying  an  'altname'
              for the node. This is an alternative name by which the node is known, that resolves to another IP address used on the other ethernet
              adapter(s). You can optionally specify a different port and/or multicast address for each altname in  use.  Up  to  9  altnames  (10
              interfaces in total) can be used.

              Note  that if you are using the DLM with cman/corosync then you MUST tell it to use SCTP as it's communications protocol as TCP does
              not support multihoming.

                <clusternode name="nd1" nodeid="1">
                   <altname name="nd1a" port="6809" mcast="229.192.0.2"/>
                </clusternode>

                <dlm protocol="sctp"/>

       Multicast network configuration
              cman uses multicast UDP packets to communicate with other nodes in the cluster.  By default it will  generate  a  multicast  address
              using  239.192.x.x  where x.x is the 16bit cluster ID number split into bytes. This, in turn is generated from a hash of the cluster
              name though it can be specified explicitly. The purpose of this is to allow multiple 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 specifying 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>

       corosync security key
              All traffic sent out by cman/corosync is encrypted. By default 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/cluster/corosync.key">
                </cman>

              Note that this only applies to cluster communication. The DLM does not encrypt traffic.

       Other corosync parameters
              When corosync is started by cman (cman_tool runs corosync), the corosync.conf file is not used.  Many of the  configuration  parame-
              ters  listed in corosync.conf can be set in cluster.conf instead.  Cman will read corosync parameters from the following sections in
              cluster.conf and load them into corosync:

                <cluster>
                  <totem />
                  <event />
                  <aisexec />
                  <group />
                </cluster>

              See the corosync.conf(5) man page for more information on keys that are valid for these sections.  Note that settings in the  <clus-
              ternodes>  section  will  override settings in the sections above, and options on the cman_tool command line will override both.  In
              particular, settings like bindnetaddr, mcastaddr, mcastport and nodeid will always be replaced by values in <clusternodes>.

              Cman uses different defaults for some of the corosync parameters listed in corosync.conf(5).  If you wish to use a non-default  set-
              ting, they can be configured in cluster.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 >
                />
                <aisexec user="root" group="root" />

              Here's how to set the token timeout to five seconds:

                <totem token="5000"/>

SEE ALSO

       cluster.conf(5), corosync.conf(5), cman_tool(8)

                                                                                                                                           cman(5)