a big table add partition in galera cluster?

[Ljr Yang]

Hi, 

    Recently, we want to add partition in mariadb galera cluster,  table size about 20GB, 

    if run alter table or pt-online-schema-change will block the entire cluster,  In order to add partition ,Is it must run in wsrep_osu_method="RSU"? 

    please help ,thanks.