anchor.diff:  chasing the primary being quickly sent back and forth between the nodes, potentially making them both go OOM. {GIT}12573[#12573]
   
   [float]
  -=== Do not allow stale shards to automatically be promoted to primary (STATUS: UNRELEASED, v5.0.0)
  +=== Do not allow stale shards to automatically be promoted to primary (STATUS: DONE, v5.0.0)
   
   In some scenarios, after the loss of all valid copies, a stale replica shard can be automatically assigned as a primary, preferring old data
   to no data at all ({GIT}14671[#14671]). This can lead to a loss of acknowledged writes if the valid copies are not lost but are rather
  
positive.code: stale shard copy.
  
  [float]
  === Make index creation resilient to index closing and full cluster crashes (STATUS: UNRELEASED, v5.0.0)
  
  Recovering an index requires a quorum (with an exception for 2) of shard copies to be available to allocate a primary. This means that
  a primary cannot be assigned if the cluster dies before enough shards have been allocated ({GIT}9126[#9126]). The same happens if an index
  
negative.code: 
  
  [float]
  === Loss of documents during network partition (STATUS: DONE, v5.0.0)
  
  If a network partition separates a node from the master, there is some window of time before the node detects it. The length of the window is dependent on the type of the partition. This window is extremely small if a socket is broken. More adversarial partitions, for example, silently dropping requests without breaking the socket can take longer (up to 3x30s using current defaults).
  
  