drbd não pode iniciar o Não é possível carregar o módulo drbd

estou tentando aprender drbd com centoOS 6.3 na caixa virtual, tenho duas vm configuradas, o nó 1 é original, o nó 2 é clonado do nó 1, mas não consigo iniciar 'service drbd start' há um erro mensagem 'iniciando recursos DRBD: Não é possível carregar o módulo drbd', enquanto o nó 2 pode iniciar o comando, aqui está a configuração

[root@localhost db]# cat /etc/drbd.conf

# You can find an example in  /usr/share/doc/drbd.../drbd.conf.example

    #include "drbd.d/global_common.conf";
    #include "drbd.d/*.res";

    global {
        # do not participate in online usage survey
        usage-count no;
    }

    resource data {

        # write IO is reported as completed if it has reached both local
        # and remote disk
        protocol C;

        net {
            # set up peer authentication
            cram-hmac-alg sha1;
            shared-secret "s3cr3tp@ss";
            # default value 32 - increase as required
            max-buffers 512;
            # highest number of data blocks between two write barriers
            max-epoch-size 512;
            # size of the TCP socket send buffer - can tweak or set to 0 to
            # allow kernel to autotune
            sndbuf-size 0;
        }

        startup {
            # wait for connection timeout - boot process blocked
            # until DRBD resources are connected
            wfc-timeout 30;
            # WFC timeout if peer was outdated
            outdated-wfc-timeout 20;
            # WFC timeout if this node was in a degraded cluster (i.e. only had one
            # node left)
            degr-wfc-timeout 30;
        }

        disk {
            # the next two are for safety - detach on I/O error
            # and set up fencing - resource-only will attempt to
            # reach the other node and fence via the fence-peer
            # handler
            on-io-error detach;
            fencing resource-only;
            # no-disk-flushes; # if we had battery-backed RAID
            # no-md-flushes; # if we had battery-backed RAID
            # ramp up the resync rate
            # resync-rate 10M;
        }
        handlers {
            # specify the two fencing handlers
            # see: http://www.drbd.org/users-guide-8.4/s-pacemaker-fencing.html
            fence-peer "/usr/lib/drbd/crm-fence-peer.sh";
            after-resync-target "/usr/lib/drbd/crm-unfence-peer.sh";
        }
        # first node
        on node1.mycluster.org {
            # DRBD device
            device /dev/drbd0;
            # backing store device
            disk /dev/sdb;
            # IP address of node, and port to listen on
            address 192.168.1.101:7789;
            # use internal meta data (don't create a filesystem before
            # you create metadata!)
            meta-disk internal;
        }
        # second node
        on node2.mycluster.org {
            # DRBD debice
            device /dev/drbd0;
            # backing store device
            disk /dev/sdb;
            # IP address of node, and port to listen on
            address 192.168.1.102:7789;
            # use internal meta data (don't create a filesystem before
            # you create metadata!)
            meta-disk internal;
        }
    }

alguem sabe qual é o problema?