我有以下6个数据节点（dn）：
dn1-6核6gb-3个map插槽和3个reduce插槽
dn2-6核6gb-3个map插槽和3个缩减插槽
dn3-6核6gb-3个map插槽和3个REDUCT插槽
dn4-6核6gb-3个map插槽和3个REDUCT插槽
dn5-6核6gb-3个map插槽和3个REDUCT插槽
dn6-6核6gb-3个map插槽和3个REDUCT插槽

案例1（可用性）

State of the system
===================
dn1 has 1 mapper running from another job Y; so 2 mapper slots are free
dn2 has 1 mapper running from another job Y; so 2 mapper slots are free
dn3 has 1 mapper running from another job Y; so 2 mapper slots are free
dn4 has 1 mapper running from another job Y; so 2 mapper slots are free
dn5 has 0 mappers running; so 3 mapper slots are free
dn6 has 0 mappers running; so 3 mapper slots are free
State of my input file
======================
I have a file that is distributed in 3 64MB blocks with RF 3 in the following way: 
R1(dn1,dn2,dn3) 
R2(dn2,dn3,dn4) 
R3(dn3,dn4,dn5)

当我在这个文件上运行一个job x时，需要创建3个对应于3个数据块的Map器。

问题

In FIFO: Is Job X still put on the queue waiting for Y to finish considering its a FIFO scheduler and other jobs are running even though "there are other mapper slots free in the same machine" or the FIFO logic kicks in only when no more resources are available in the system and the jobs consequently has to be put on the queue?
In Capacity Scheduler: What would the behavior be?
In Fair Share Scheduler: What would the behavior be?

案例2（稀缺性）

State of the system
===================
dn1 has 3 mappers running from another job Y; so 0 mapper slots are free
dn2 has 3 mappers running from another job Y; so 0 mapper slots are free
dn3 has 3 mappers running from another job Y; so 0 mapper slots are free
dn4 has 3 mappers running from another job Y; so 0 mapper slots are free
dn5 has 3 mappers running from another job Y; so 0 mapper slots are free
dn6 has 0 mappers running; so 3 mapper slots are free

我有一个文件，它以364MB的块和rf 3以以下方式分发：

R1(dn1,dn2,dn3) 
R2(dn2,dn3,dn4) 
R3(dn3,dn4,dn5)

当我在这个文件上运行一个job x时，需要创建3个对应于3个数据块的Map器。

问题

现在发生了什么：

- Are the 3 mapper tasks created on dn6 (which does not have any of the data blocks of the input file yet) and corresponding data block transferred over the network from say dn1 to dn6?
        - If yes, does this same behaviour show in the case of all the three schedulers: FIFO/Capacity/Fair Share?
            - If no, then can you elaborate on the behaviour shown for this use case in case of:
                - FIFO Scheduler
                - Capacity Scheduler
                - Fair Share Scheduler