This information applies to version 2.x of Elasticsearch. For the most up to date information, see the current version of the Elasticsearch Reference.
On an empty cluster with no indices, this will return something like the following:
- All primary and replica shards are active.
- All primary shards are active, but not all replica shards are active.
- Not all primary shards are active.
In the rest of this chapter, we explain what primary and replica shards are and explain the practical implications of each of the preceding colors.