Two of them, I believe - the master for the cluster as a whole, and, for any individual job, its driver.
I wasn't really meaning to say that a Spark cluster is as robust as a mainframe (though maybe someone's figured out some tricks), more that I could totally see some sales folks conducting the same demo using something like Spark.
I wasn't really meaning to say that a Spark cluster is as robust as a mainframe (though maybe someone's figured out some tricks), more that I could totally see some sales folks conducting the same demo using something like Spark.