Data fails to transfer, and

Data did not get indexed.

Check Outbound XDCR Operations

In Couchbase Web Console under Data Buckets, Click | Bucket-name | Outbound XDCR to view information about data replication via XDCR to Elasticsearch. The statistics in this section will indicate the rate of data transfer between Couchbase Server and Elasticsearch. For more information about monitoring XDCR, see Couchbase Server, Manual, Monitoring Replication.

Check Couchbase Plug-in for Elasticsearch Log files

The plug-in logs to the same directory and file that Elasticsearch uses at the root of a Elasticsearch node. For production systems the log is at /var/log/elasticsearch.

Compare Document Count

You can compare the number of documents in Couchbase Server with the number of documents in your Elasticsearch cluster. Be aware that this assumes your Couchbase Server has a static number of items, for instance your cluster is in a test environment where the number of documents is set and you do not add more during replication. In Couchbase Web Console, click on Data Buckets. The number of documents for a named bucket appears under Item Count:

Figure 4.1. Item Count in Couchbase Server

In this example we have 7303 items. Then we get the number of documents indexed by Elasticsearch:

curl http://[elasticsearch_host]:9200/[index-name]/couchbaseDocument/_count

Upon success, you get the following result:

{"count":7303,"_shards":
	{
	"total":5,"successful":5,"failed":0
	}
}

So the count result is the same number as the number of items from Couchbase Web Console; this provides assurance that all items from Couchbase are transferred and indexed.