Collapsing a redis cluster from 6 nodes into 2.

gistfile1.txt

1.)   [1]    [2]    [3]     Six node cluster
      [4]    [5]    [6]

2.)   [1]    [2] <= [3]     Hosts 2 and 5 replicate from 3 and 6 respectively.
      [4]    [5] <= [6]     Once caught up, the clients are updated to point
                            to 2 and 5 instead, and 3 and 6 are terminated.

3.)   [1] <= [2]            Repeat.
      [4] <= [5]

4.)   [1]                   Now you're left with a two node cluster.
      [4]