|  | title Replication - Split Brain | 
|  |  | 
|  | participant Client1 | 
|  | participant Instance1 | 
|  | participant Instance2 | 
|  | participant Client2 | 
|  |  | 
|  | state over Client1, Client2, Instance1, Instance2: W0 | 
|  | state over Client1 : W0 -> W1 | 
|  | Client1 -> +Instance1: Push W1 | 
|  | Instance1 -> -Client1: Ack W1 | 
|  | state over Instance1 : W0 -> W1 | 
|  | state over Instance1 : Crash | 
|  |  | 
|  | state over Client2 : W0 -> W2 | 
|  | Client2 -> +Instance2: Push W2 | 
|  | Instance2 -> -Client2 : Ack W2 | 
|  | state over Instance2 : W0 -> W2 | 
|  |  | 
|  | state over Instance1:  Restart | 
|  |  | 
|  | par | 
|  | Instance2->Instance1: Replicate W2 | 
|  | Instance1->Instance2: Replicate W1 | 
|  | end | 
|  |  | 
|  | parallel { | 
|  | state over Instance2: W0 -> W1 | 
|  | state over Instance1: W0 -> W2 | 
|  | state over Client1: W0 -> W1 | 
|  | state over Client2: W0 -> W2 | 
|  | } | 
|  |  | 
|  | note over Instance1, Instance2 | 
|  | Instances status diverged | 
|  | and is even swapped from | 
|  | original | 
|  | end note |