'Get the default storage group.
:param array: the array serial number
:param srp: the pool name
:param slo: the SLO
:param workload: the workload
:param do_disable_compression: flag for disabling compression
:param is_re: flag for replication
:returns: the storage group dict (or None), the storage group name'

def get_vmax_default_storage_group(self, array, srp, slo, workload, do_disable_compression=False, is_re=False):

    storagegroup_name = self.utils.get_default_storage_group_name(srp, slo, workload, do_disable_compression, is_re)
    storagegroup = self.get_storage_group(array, storagegroup_name)
    return (storagegroup, storagegroup_name)
