---
title: "Scale a Kafka cluster"
sidebar_label: "Scale a cluster"
sidebar_position: 11
description: "How to change the configuration of Kafka cluster nodes"
---

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# Scale a Kafka cluster

The Kafka Managed Database cluster can be [scaled](#resize-cluster). For example:

* increase vCPU and RAM to improve cluster performance;
* change the configuration line with a local disk to another line with a local disk — the disk size must be larger than in the previous configuration, while the number of vCPUs and RAM can be reduced or increased. It is not possible to change a configuration line with one type of disk to a line with another type of disk.

See the list of [node configurations](/managed-databases/kafka/configurations.mdx).

While changes are being applied, the master node will be stopped, and the cluster will be temporarily unavailable for read and write operations.

The time required to change the configuration depends on the volume of data in the cluster.

## Scale a cluster \{#resize-cluster}

Scale the cluster when user activity is at its lowest.

1. In the [Dashboard](https://my.selectel.ru/vpc/default/dbaas/), on the top menu, click **Products** and select **Managed Databases**.

2. Open the **Active** tab.

3. Open the cluster page → **Settings** tab.

4. Click **Change configuration**.

5. Select a different [configuration](/managed-databases/kafka/configurations.mdx). You can:

   * select a configuration with a larger disk size only;
   * decrease or increase the number of vCPUs and RAM;
   * change a configuration line with a local disk to another line with a local disk. You cannot change a configuration line with one disk type to a line with a different disk type.

6. Click **Save**.

7. After scaling, [clear the DNS cache](#clear-dns-cash).

8. Verify that the cluster has scaled correctly.

## Clear DNS cache \{#clear-dns-cash}

<Tabs queryString="clear-dns-cash">
  <TabItem value="ubuntudebian" default>
    <TabItemLabel>
      Ubuntu/Debian
    </TabItemLabel>

    1. Open the CLI.
    2. Clear the DNS cache:

       ```bash
       sudo systemctl restart systemd-resolved
       ```
  </TabItem>

  <TabItem value="centos">
    <TabItemLabel>
      CentOS
    </TabItemLabel>

    1. Open the CLI.
    2. Clear the DNS cache:

       ```bash
       sudo dscacheutil -flushcache
       ```
  </TabItem>

  <TabItem value="macos">
    <TabItemLabel>
      macOS
    </TabItemLabel>

    1. Open the CLI.
    2. Clear the DNS cache:

       ```bash
       sudo systemctl restart network
       ```
  </TabItem>

  <TabItem value="windows">
    <TabItemLabel>
      Windows
    </TabItemLabel>

    1. Open the CLI with administrator privileges.
    2. Clear the DNS cache:

       ```bash
       ipconfig /flushdns
       ```
  </TabItem>
</Tabs>

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