Parameter	Default value	Description
Indices alias name	magento2	The default alias put by the module on Magento’s related indices. An alias per store and entity type will be generated with the following format : [indices_alias_name]_[store_code]_[entity_type]. E.g. : magento2_default_catalog_product.
Indices name pattern	_	The horodated pattern used when creating new index. An index name per store and entity type, based on the horodated pattern, will be generated with the following format : [indices_alias_name]_[store_code]_[entity_type]_[horodated_pattern]. The E.g. : magento2_default_catalog_product_20160304_094708.
Number of shards per index	1	The number of shards per index. A shard is a single Lucene instance and they are distributed by ElasticSearch amongst all nodes in the cluster. You can see the Shard definition on the ElasticSearch glossary for more informations.
Number of replicas per index	0	The number of replicas shards per index. Main purposes of replica shards is for failover : if the node holding a primary shard dies, a replica is promoted to the role of primary. You can read more about Replica Shards on the ElasticSearch documentation.