Returns a vim.HostScsiDisk if the host cache is configured on the specified
    host, other wise returns None

    host_ref
        The vim.HostSystem object representing the host that contains the
        requested disks.

    host_cache_manager
        The vim.HostCacheConfigurationManager object representing the cache
        configuration manager on the specified host. Default is None. If None,
        it will be retrieved in the method

def get_host_cache(host_ref, host_cache_manager=None):
    '''
    Returns a vim.HostScsiDisk if the host cache is configured on the specified
    host, other wise returns None

    host_ref
        The vim.HostSystem object representing the host that contains the
        requested disks.

    host_cache_manager
        The vim.HostCacheConfigurationManager object representing the cache
        configuration manager on the specified host. Default is None. If None,
        it will be retrieved in the method
    '''
    hostname = get_managed_object_name(host_ref)
    service_instance = get_service_instance_from_managed_object(host_ref)
    log.trace('Retrieving the host cache on host \'%s\'', hostname)
    if not host_cache_manager:
        traversal_spec = vmodl.query.PropertyCollector.TraversalSpec(
            path='configManager.cacheConfigurationManager',
            type=vim.HostSystem,
            skip=False)
        results = get_mors_with_properties(service_instance,
                                           vim.HostCacheConfigurationManager,
                                           ['cacheConfigurationInfo'],
                                           container_ref=host_ref,
                                           traversal_spec=traversal_spec)
        if not results or not results[0].get('cacheConfigurationInfo'):
            log.trace('Host \'%s\' has no host cache', hostname)
            return None
        return results[0]['cacheConfigurationInfo'][0]
    else:
        results = get_properties_of_managed_object(host_cache_manager,
                                                   ['cacheConfigurationInfo'])
        if not results:
            log.trace('Host \'%s\' has no host cache', hostname)
            return None
        return results['cacheConfigurationInfo'][0]