Galera has a copule of options to sync mariadb cluster.
Default value is mysqldump which is slow, except for small data-sets, but is the most tested option.
rsync option is much faster than mysqldump on large data-sets.
So add --wsrep_sst_method value.
Change-Id: Ide03801b2472fa3d4f76bbe32e75bf6e618ac7e1
d4f7fa5775