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3rd chunk of `content/manuals/engine/storage/drivers/device-mapper-driver.md`
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single block device. If you need to use multiple block devices,
[configure direct-lvm mode manually](#configure-direct-lvm-mode-manually) instead.
The following new configuration options are available:

| Option                          | Description                                                                                                                                                                        | Required? | Default | Example                            |
|:--------------------------------|:-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|:----------|:--------|:-----------------------------------|
| `dm.directlvm_device`           | The path to the block device to configure for `direct-lvm`.                                                                                                                        | Yes       |         | `dm.directlvm_device="/dev/xvdf"`  |
| `dm.thinp_percent`              | The percentage of space to use for storage from the passed in block device.                                                                                                        | No        | 95      | `dm.thinp_percent=95`              |
| `dm.thinp_metapercent`          | The percentage of space to use for metadata storage from the passed-in block device.                                                                                                   | No        | 1       | `dm.thinp_metapercent=1`           |
| `dm.thinp_autoextend_threshold` | The threshold for when lvm should automatically extend the thin pool as a percentage of the total storage space.                                                                   | No        | 80      | `dm.thinp_autoextend_threshold=80` |
| `dm.thinp_autoextend_percent`   | The percentage to increase the thin pool by when an autoextend is triggered.                                                                                                       | No        | 20      | `dm.thinp_autoextend_percent=20`   |
| `dm.directlvm_device_force`     | Whether to format the block device even if a filesystem already exists on it. If set to `false` and a filesystem is present, an error is logged and the filesystem is left intact. | No        | false   | `dm.directlvm_device_force=true`   |

Edit the `daemon.json` file and set the appropriate options, then restart Docker
for the changes to take effect. The following `daemon.json` configuration sets all of the
options in the table above.

```json
{
  "storage-driver": "devicemapper",
  "storage-opts": [
    "dm.directlvm_device=/dev/xdf",
    "dm.thinp_percent=95",
    "dm.thinp_metapercent=1",
    "dm.thinp_autoextend_threshold=80",
    "dm.thinp_autoextend_percent=20",
    "dm.directlvm_device_force=false"
  ]
}
```

See all storage options for each storage driver in the
[daemon reference documentation](/reference/cli/dockerd/#options-per-storage-driver)

Restart Docker for the changes to take effect. Docker invokes the commands to
configure the block device for you.

> [!WARNING]
> Changing these values after Docker has prepared the block device for you is
> not supported and causes an error.

You still need to [perform periodic maintenance tasks](#manage-devicemapper).

#### Configure direct-lvm mode manually

The procedure below creates a logical volume configured as a thin pool to
use as backing for the storage pool. It assumes that you have a spare block
device at `/dev/xvdf` with enough free space to complete the task. The device
identifier and volume sizes may be different in your environment and you
should substitute your own values throughout the procedure. The procedure also
assumes that the Docker daemon is in the `stopped` state.

1.  Identify the block device you want to use. The device is located under
    `/dev/` (such as `/dev/xvdf`) and needs enough free space to store the
    images and container layers for the workloads that host runs.
Title: Configuring direct-lvm mode with Docker and manually
Summary
The text describes how to configure direct-lvm mode for the devicemapper storage driver in Docker, both automatically and manually. Docker can manage direct-lvm with options like `dm.directlvm_device` (required), `dm.thinp_percent`, `dm.thinp_metapercent`, `dm.thinp_autoextend_threshold`, `dm.thinp_autoextend_percent`, and `dm.directlvm_device_force`, configurable in `daemon.json`. Manual configuration is necessary for multiple block devices and involves creating a thin pool logical volume. The text emphasizes to set appropriate options in `daemon.json` and then restart Docker for the changes to take effect. After Docker prepares the block device, changing values is not supported and causes an error.