anchor.diff:  Other safeguards are tracked in the meta-issue {GIT}11511[#11511].
   
   [float]
  -=== The _version field may not uniquely identify document content during a network partition (STATUS: ONGOING)
  -
  -When a primary has been partitioned away from the cluster there is a short period of time until it detects this. During that time it will continue
  -indexing writes locally, thereby updating document versions. When it tries to replicate the operation, however, it will discover that it is
  -partitioned away. It won't acknowledge the write and will wait until the partition is resolved to negotiate with the master on how to proceed.
  -The master will decide to either fail any replicas which failed to index the operations on the primary or tell the primary that it has to
  -step down because a new primary has been chosen in the meantime. Since the old primary has already written documents, clients may already have read from
  -the old primary before it shuts itself down. The version numbers of these reads may not be unique if the new primary has already accepted
  -writes for the same document (see {GIT}19269[#19269]).
  -
  -We are currently implementing Sequence numbers {GIT}10708[#10708] which better track primary changes. Sequence numbers thus provide a basis
  -for uniquely identifying writes even in the presence of network partitions and will replace `_version` in operations that require this.
  -
  -[float]
   === Relocating shards omitted by reporting infrastructure (STATUS: ONGOING)
   
   Indices stats and indices segments requests reach out to all nodes that have shards of that index. Shards that have relocated from a node
  
positive.code: The new tests are run continuously in our testing farm and are passing. We are also working on running Jepsen independently to verify
  that no failures are found.
  
  [float]
  === Replicas can fall out of sync when a primary shard fails (STATUS: ONGOING)
  
  When a primary shard fails, a replica shard will be promoted to be the
  primary shard. If there is more than one replica shard, it is possible
  for the remaining replicas to be out of sync with the new primary
  shard. This is caused by operations that were in-flight when the primary
  shard failed and may not have been processed on all replica
  shards. Currently, the discrepancies are not repaired on primary
  promotion but instead would be repaired if replica shards are relocated
  (e.g., from hot to cold nodes); this does mean that the length of time
  which replicas can be out of sync with the primary shard is
  unbounded. Sequence numbers {GIT}10708[#10708] will provide a mechanism
  for syncing the remaining replicas with the newly-promoted primary
  shard.
  
  == Completed
  
  [float]
  === Repeated network partitions can cause cluster state updates to be lost (STATUS: DONE, v7.0.0)
  
negative.code: improvements throughout this page to provide the full context.
  
  If you’re interested in more on how we approach ensuring resiliency in
  Elasticsearch, you may be interested in Igor Motov’s talk
  http://www.elastic.co/videos/improving-elasticsearch-resiliency[Improving Elasticsearch Resiliency].
  
  You may also be interested in our blog post
  