# Explanation of Monitoring Metrics

|Category of Monitoring Metrics|Monitoring Metrics|Explanation|
|--- |--- |--- |
|Kafka Metrics|Incoming Message Rate (Per/s)|It is the rate of messages (per/s) covering all topics, averaged over one minute.|
|:::|Incoming Data Rate (B/s)|It is the rate of incoming data (B/s) covering all topics, averaged over one minute.|
|:::|Outgoing Data Rate (B/s)|It is the rate of outgoing data (B/s) covering all topics, averaged over one minute.|
|:::|Failed Consumer Requests (Per/s)|It is the number of failed requests by consumers, averaged over one minute.|
|:::|Failed Producer Requests (Per/s)|It is the number of failed requests by producers, averaged over one minute.|
|:::|Message Rejected by Broker (B/s)|It is the amount of messages rejected by broker, averaged over one minute.|
|:::|Leader Election Speed (ms)|It is the speed at which a leader is elected when the Broker is down. The election should be completed in as short a time as possible by the cluster.|
|:::|Number of Live Controllers (N)|At the same time, there can only be one controller in the cluster at most. It is same to the following metric of the number of management nodes (N).|
|:::|Producer Request Response Time (ms)|It is the average response time of the producer.|
|:::|Producer QPS (Per/s)|It is the QPS of the producer, averaged over one minute.|
|:::|Consumer Request Response Time (ms)|It is the average response time of the consumer.|
|:::|Consumer QPS (Per/s)|It is the QPS of the consumer, averaged over one minute.|
|:::|Number of Live Kafka Nodes (N)|It is the number of live nodes in the cluster, which should be same to the number of cluster nodes.|
|:::|Maximum Message Lag Between Follower and Leader (N)|It is the maximum number of messages follower lag behind leader replica.|
|:::|Total Number of Partitions on This Node (N)|It is the total number of partitions on this node.|
|:::|Total Number of Leader Partitions on This Node (N)|It is the total number of leader partitions on this node.|
|:::|Total Number of Unreplicated Partitions (N)|It is the number of partitions waiting for replication, the normal value is 0|
|:::|ISR Shrink Rate (Per/s)|The shrinking rate of ISR.<\br> If a broker goes down, some partition's ISR will shrink.<\br> When the broker is back online, ISR will expand once its replica is fully caught up.<\br> Besides, under normal circumstances, this value and the following expansion rate are both 0.|
|:::|ISR Expansion Rate (Per/s)|The expansion rate of ISR. See the shrinking rate of ISR for details.|
|:::|Number of Management Nodes (N)|Whether the current broker is a controller. <\br> Only one broker has this value as 1 in the cluster, others as 0. If all are 0, the cluster has problems.|
|:::|Total Number of Offline Partitions (N)|The number of offline partitions.|
|Node Metrics|CPU Utilization (%)|The CPU utilization of the node.|
|:::|Disk Read/Write Throughput (Kb/s)|The throughput of disk read and write.|
|:::|Disk Read/Write Times (Per/s)|The times of disk read and write.|
|:::|Network Interface In/Out Bandwidth (Kb/s)|The bandwidth of network interface in/out.|
|:::|Network Interface In/Out Packet Volume (Per/s)|The packet volume of network interface in/out.|
|:::|Memory Utilization (%)|The memory utilization of the node.|
|:::|Data Disk Utilization (%)|The utilization of data disk of node.|
|:::|System Disk Utilization (%)|The utilization of system disk of node.|
|Zookeeper Metrics|Current Active Connections of zk (N)|The number of current active connections of zk.|
|:::|Max Request Delay of zk (ms)|The max request delay of zk.|
|:::|Average Request Delay of zk (ms)|The average request delay of zk.|
|:::|Min Request Delay of zk (ms)|The min request delay of zk.|
|:::|Total Responses Recieved by zk (10k)|The total responses recieved by zk.|
|:::|Total Responses Sent by zk (10k)|The total responses sent by zk.|
|:::|Pending Connections of zk (N)|The number of pending connections of zk.|
|:::|Watcher Number (N)|Watch mechanism used for active notifications by Zookeeper when data is changed.<\br> Watch could be attached to each node, so if there are 10k nodes in an application,<\br> there might be 10k watches (or even more) in Zookeeper.|
|:::|Number of Znodes (N)|Znode is the node of Zookeeper, similar to the directory or file of a file system.|