Document woes between auto-expand-replicas and allocation filtering
Relates to
@@ -103,9 +103,14 @@ specific index module:
`index.auto_expand_replicas`::
- Auto-expand the number of replicas based on the number of available nodes.
+ Auto-expand the number of replicas based on the number of data nodes in the cluster.
Set to a dash delimited lower and upper bound (e.g. `0-5`) or use `all`
for the upper bound (e.g. `0-all`). Defaults to `false` (i.e. disabled).
+ Note that the auto-expanded number of replicas does not take any other allocation
+ rules into account, such as <<allocation-awareness,shard allocation awareness>>,
+ <<shard-allocation-filtering,filtering>> or <<allocation-total-shards,total shards per node>>,
+ and this can lead to the cluster health becoming `YELLOW` if the applicable rules
+ prevent all the replicas from being allocated.
`index.refresh_interval`::
