> For the complete documentation index, see [llms.txt](https://platform9.com/kb/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://platform9.com/kb/pmk/solutions/error-initializing-docker-devicemapper-non-existing-device-dock.md).

# Error Initializing Docker: "devicemapper: Non existing device docker--vg-docker--pool"

## Problem

Docker is failing to start with the following error message.

{% tabs %}
{% tab title="None" %}

```none
Error starting daemon: error initializing graphdriver: devicemapper: Non existing device docker--vg-docker--pool
```

{% endtab %}
{% endtabs %}

## Environment

* Platform9 Managed Kubernetes - All Versions
* Docker

## Cause

The prerequisite logical volume for Docker was not named correctly as per the storage options in */etc/docker/daemon.json*.

## Resolution

**Note**: The following scenarios assume that the logical volume name is intended to be *docker-pool*, as per the error message.

### Option #1

1. Rename the logical volume.

{% tabs %}
{% tab title="None" %}

```none
# lvrename docker-vg/[lv-name] docker-vg/docker-pool
```

{% endtab %}
{% endtabs %}

### Option #2

1. Modify */etc/docker/daemon.json* to match the path of the logical volume that was created.

{% tabs %}
{% tab title="None" %}

```none
"storage-opts": [ "dm.fs=xfs", "dm.thinpooldev=/dev/mapper/docker--vg-docker--pool", "dm.use_deferred_removal=true" ]
```

{% endtab %}
{% endtabs %}

## Additional Information

[Preparing CentOS or RHEL 7 system for running Platform9 Managed Kubernetes](https://docs.platform9.com/support/preparing-centos-7-system-running-containers/)


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