this is quite fragile and will break with additional disk types in storage. Please use for it this method https://github.com/yast/yast-storage/blob/master/src/modules/Storage.rb#L1930

for blacklisting the nearist method is https://github.com/yast/yast-storage/blob/master/src/modules/Storage.rb#L5019 . Maybe you should ask arvin if there is method for your needs, as it should live in storage and not here.