The Fetcher Lag Metrics group contains metrics regarding the lag in the number of messages per follower replica. The metrics available are:
- Aggregated Fetcher Consumer Lag
Aggregated Fetcher Consumer Lag
This metric aggregates lag in messages per follower replica reported under kafka.server:type=FetcherLagMetrics,name=ConsumerLag,clientId=([-.\w]+),topic=([-.\w]+),partition=([0-9]+) at a broker level. This allows monitoring the broker capability to keep in sync with partitions that it is replicating. The expected value for this metric should be 0 or very low indicating the broker is keeping up with replication. If it is increasing or very high that indicates a problem and should be monitored and investigated.
Please note that brokers would not report this metric if it is not following a partition. For example all topics in the cluster is created with a replication factor of 1.