concurrentRequests:${SW_STORAGE_ES_CONCURRENT_REQUESTS:2}# the number of concurrent requests
```
Read the [ElasticSearch storage FAQ](../../FAQ/ES-Server-FAQ.md) if you are new to ElasticSearch. And recommend read more about these configuration from ElasticSearch official document. This effects the performance of ElasticSearch very much.
### ElasticSearch 6 with Jaeger trace extension
This implementation shares most of `elasticsearch`, just extend to support zipkin span storage.