Comment 102 for bug 1185756

@Stefan, thanks for the reply. It seems my information was not that clear. Here some more so it is more clear what my problem was.

The problem is with the pacemaker drbd agent:
/usr/lib/ocf/resource.d/linbit/drbd

Here a snippet of this agent:
-----------------
drbd_start() {
        local rc
        local status
        local first_try=true

        rc=$OCF_ERR_GENERIC

        if ! is_drbd_enabled; then
                do_cmd modprobe -s drbd `$DRBDADM sh-mod-parms` || {
                        ocf_log err "Cannot load the drbd module.";
                        return $OCF_ERR_INSTALLED
                }
                drbd_validate_all
                ocf_log debug "$DRBD_RESOURCE start: Module loaded."
        fi
------------------

The line with "drbd_validate_all" is the one I added. Without this line, drbd will not work after reboot.
I hope this clearify a bit more.