---
id: 43720cec-bb6d-425d-b437-faaebe5b22d5
---
# Kafka Cluster Replication Factor Check
---

In a Kafka cluster, replication factor is the number of copies of a topic's partitions across different brokers. The replication factor is set at the time of topic creation and cannot be changed once the topic is created. In case the replication factor is less than the minimum required number, there is a risk of data loss if one or more brokers go down. This incident type involves checking the replication factor of Kafka clusters to ensure that the number of replicas is sufficient, and that data is safe in case of a broker failure.

### Parameters
```shell
export ZOOKEEPER_HOST="PLACEHOLDER"

export TOPIC_NAME="PLACEHOLDER"

export ZOOKEEPER_PORT="PLACEHOLDER"

export PATH_TO_KAFKA_HOME="PLACEHOLDER"

export REPLICATION_FACTOR="PLACEHOLDER"
```

## Debug

### Check the replication factor of a specific topic
```shell
kafka-topics.sh --zookeeper ${ZOOKEEPER_HOST}:${ZOOKEEPER_PORT} --describe --topic ${TOPIC_NAME}
```

### Check the replication factor of all topics in a cluster
```shell
kafka-topics.sh --zookeeper ${ZOOKEEPER_HOST}:${ZOOKEEPER_PORT} --list | xargs -n1 kafka-topics.sh --zookeeper ${ZOOKEEPER_HOST}:${ZOOKEEPER_PORT} --describe --topic
```

### Check the number of brokers in a cluster
```shell
zookeeper-shell.sh ${ZOOKEEPER_HOST}:${ZOOKEEPER_PORT} ls /brokers/ids | grep '\[' | awk -F'[][]' '{print $2}' | wc -l
```

### Check the number of replicas of a topic's partitions
```shell
kafka-topics.sh --zookeeper ${ZOOKEEPER_HOST}:${ZOOKEEPER_PORT} --describe --topic ${TOPIC_NAME} | grep -i replica
```

### Check the number of in-sync replicas of a topic's partitions
```shell
kafka-topics.sh --zookeeper ${ZOOKEEPER_HOST}:${ZOOKEEPER_PORT} --describe --topic ${TOPIC_NAME} | grep -i isr
```

## Repair

### Increase the replication factor of the topic so that it meets the minimum required number. This can be done using the Kafka command line tools or the Kafka API.
```shell


#!/bin/bash



# Set variables

KAFKA_HOME=${PATH_TO_KAFKA_HOME}

TOPIC=${TOPIC_NAME}

REPLICATION_FACTOR=${REPLICATION_FACTOR}



# Increase replication factor of the topic

$KAFKA_HOME/bin/kafka-topics.sh --zookeeper $ZOOKEEPER_HOST:$ZOOKEEPER_PORT --alter --topic $TOPIC --partitions 1 --replication-factor $REPLICATION_FACTOR


```

In a Kafka cluster, replication factor is the number of copies of a topic's partitions across different brokers. The replication factor is set at the time of topic creation and cannot be changed once the topic is created. In case the replication factor is less than the minimum required number, there is a risk of data loss if one or more brokers go down. This incident type involves checking the replication factor of Kafka clusters to ensure that the number of replicas is sufficient, and that data is safe in case of a broker failure.


This incident type refers to a situation where there is an issue with the communication between Kafka brokers due to network partitioning. A network partition is a situation where a network is split into two or more parts, and communication between them is disrupted. This issue can lead to data inconsistency, loss of messages, delayed message delivery, and other related problems. As a result, it is important to quickly detect and resolve these incidents to prevent any downstream impact on the system.


Parameters

This incident type refers to when a Kafka node runs out of storage space to store data. This can cause issues with data processing and storage, potentially leading to data loss and system downtime.


Kafka node insufficient storage check

This incident type refers to a scenario where the liveness check for Kafka cannot reach/communicate with the host where the broker is running. This issue can arise due to various reasons such as network issues, broker failure, or configuration errors. This can result in the Kafka broker being unavailable or not responding to requests, leading to potential service disruptions or downtime.


Kafka liveness check failure.

This incident type relates to an issue with time synchronization that affects the proper functioning of a Kafka cluster. As Kafka relies on accurate time synchronization to maintain data consistency, any failure in this process can cause serious issues. The incident might cause data loss or duplication, service disruptions, or other problems that can impact the overall performance of the system. It requires immediate attention from the engineering team to investigate and resolve the root cause of the issue.


Kafka Time synchronization issue impacting Kafka cluster.

```shell
export ZOOKEEPER_HOST="PLACEHOLDER"

export TOPIC_NAME="PLACEHOLDER"

export ZOOKEEPER_PORT="PLACEHOLDER"

export PATH_TO_KAFKA_HOME="PLACEHOLDER"

export REPLICATION_FACTOR="PLACEHOLDER"
```


### Check the replication factor of a specific topic

```shell
kafka-topics.sh --zookeeper ${ZOOKEEPER_HOST}:${ZOOKEEPER_PORT} --describe --topic ${TOPIC_NAME}
```

### Check the replication factor of all topics in a cluster

```shell
kafka-topics.sh --zookeeper ${ZOOKEEPER_HOST}:${ZOOKEEPER_PORT} --list | xargs -n1 kafka-topics.sh --zookeeper ${ZOOKEEPER_HOST}:${ZOOKEEPER_PORT} --describe --topic
```

### Check the number of brokers in a cluster

```shell
zookeeper-shell.sh ${ZOOKEEPER_HOST}:${ZOOKEEPER_PORT} ls /brokers/ids | grep '\[' | awk -F'[][]' '{print $2}' | wc -l
```

### Check the number of replicas of a topic's partitions

```shell
kafka-topics.sh --zookeeper ${ZOOKEEPER_HOST}:${ZOOKEEPER_PORT} --describe --topic ${TOPIC_NAME} | grep -i replica
```

### Check the number of in-sync replicas of a topic's partitions

```shell
kafka-topics.sh --zookeeper ${ZOOKEEPER_HOST}:${ZOOKEEPER_PORT} --describe --topic ${TOPIC_NAME} | grep -i isr
```


### Increase the replication factor of the topic so that it meets the minimum required number. This can be done using the Kafka command line tools or the Kafka API.

```shell


#!/bin/bash



# Set variables

KAFKA_HOME=${PATH_TO_KAFKA_HOME}

TOPIC=${TOPIC_NAME}

REPLICATION_FACTOR=${REPLICATION_FACTOR}



# Increase replication factor of the topic

$KAFKA_HOME/bin/kafka-topics.sh --zookeeper $ZOOKEEPER_HOST:$ZOOKEEPER_PORT --alter --topic $TOPIC --partitions 1 --replication-factor $REPLICATION_FACTOR


```


Kafka Cluster Replication Factor Check

Overview

Parameters

Debug

Check the replication factor of a specific topic

Check the replication factor of all topics in a cluster

Check the number of brokers in a cluster

Check the number of replicas of a topic's partitions

Check the number of in-sync replicas of a topic's partitions

Repair

Increase the replication factor of the topic so that it meets the minimum required number. This can be done using the Kafka command line tools or the Kafka API.

Learn more

Related Runbooks

Network Partitioning Between Kafka Brokers.

Parameters

Kafka node insufficient storage check

Kafka liveness check failure.

Support