Master Metascheduler

             +----------+  +--------+  +---------+
             |  User 1  |  | User 2 |  |  User 3 |
             +----------+  +--------+  +---------+
                  |            |          | 
                  V            V          V
                +-----------------------------+
                |    Master Metascheduler     |
                +-----------------------------+
               /          |           \        \________
              /           |            \                \
              |           |             |                | 
              V           V             V                V
      +-----------+    +-----------+  +-----------+   +-----------+
      | Cluster A |    | Cluster B |  | Cluster C |   | Cluster D |
      +-----------+    +-----------+  +-----------+   +-----------+
    

• Single meta-schedule
• Global interface: all users and clusters must agree