# Configuration

The PN configuration is to create a data directory and set up several values in the configuration file `kpnd.conf`.

1. Create a PN Data Directory
2. Install node key
3. Install `static-node.json`
4. Configure the PN with `kpnd.conf`.

## PN Data Directory Creation <a href="#pn-data-directory-creation" id="pn-data-directory-creation"></a>

Considering the fact that the size of Klaytn blockchain data is always increased, it is recommended to use a big enough storage. You may need to create the directory on your desired path.

```bash
$ mkdir -p /var/kpnd/data
```

## Install Node Key <a href="#install-node-key" id="install-node-key"></a>

In order to operate a PN, a `nodekey` is required. The KPN binary will create a new one for you if you do not have it. If you have one, you need to put your `nodekey` into the PN data directory. The way to create a `nodekey` is in the "[Before You Install](https://archive-docs.klaytn.foundation/content/installation-guide/deployment/core-cell/installation-guide/before-you-install)" section. The following command line copies the `nodekey` into the PN data directory.

```bash
$ cp nodekey /var/kpnd/data
```

## Install `static-nodes.json` <a href="#install-static-nodes-json" id="install-static-nodes-json"></a>

The `static-nodes.json` should be created from the PN operator. It contains the addresses that your PN is connected to. It is recommended to add the addresses including your CN and a PN from another Core Cell. Please contact to the Klaytn official email for more details (`bootstrap@klaytn.com` for Cypress or `baobab@klaytn.com` for Baobab).

**static-nodes.json**

```
[
  "kni://4f2f47f3bf35a2c576d3345e6e9c49b147d510c05832d2458709f63c3c90c76ead205975d944ed65e77dd4c6f63ebe1ef21d60da95952bc1e200e7487f4d9e1b@10.11.2.101:32323?discport=0&ntype=cn",
  "kni://8dee912aeda2ccfaa4fe421f015d4d75c2e3fd4aab75fa399b42767caad33531e57f3356b4a4af374593e33ec4320e1325aa2390a7be2489fa6b5724894680eb@10.11.2.102:32323?discport=0&ntype=pn"
]
```

The node URI of the PN is in the "[Before You Install](https://archive-docs.klaytn.foundation/content/installation-guide/deployment/core-cell/installation-guide/before-you-install)" section. (Note: This IP address is different from CN public IP.) The following command line copies the `static-nodes.json` file into the PN data directory.

```bash
$ cp static-nodes.json /var/kpnd/data
```

## Update the Configuration File <a href="#update-the-configuration-file" id="update-the-configuration-file"></a>

Configuration File Location:

* For the archive distribution, the config directory location defaults to `$INSTALL_PATH/kpn-linux-amd64/conf/`.
* For the package distribution, the config directory defaults to `/etc/kpnd/conf/`.

### Add Data Directory <a href="#add-data-directory" id="add-data-directory"></a>

You should update the data directory environment variable `$DATA_DIR` on the configuration file `kpnd.conf`.

```
...
DATA_DIR=/var/kpnd/data
...
```

## Fast Sync (Optional) <a href="#fast-sync-optional" id="fast-sync-optional"></a>

Each PN maintains a copy of the network's chain data. If a node is out of sync, it can obtain this data from other nodes in the network -- a process known as syncing. When a new PN is first started, it must download the entire chain data from the network.

To accelerate this process, you may perform a fast sync by downloading a snapshot of the chain data before starting the PN. This can dramatically reduce the time the PN will spend syncing on first start.

Download the latest chaindata snapshot from the [Cypress snapshot archive](http://packages.klaytn.net/cypress/chaindata/) or [Baobab snapshot archive](http://packages.klaytn.net/baobab/chaindata/). Before starting `kpnd`, extract the snapshot inside the DATA\_DIR you configured in `kpnd.conf`.

For example:

```
$ tar -C /var/kpnd/data -xvf klaytn-cypress-chaindata-latest.tar.gz
```

Or,

```
$ tar -C /var/kpnd/data -xvf klaytn-baobab-chaindata-latest.tar.gz
```

After the data is extracted, you may start the PN normally.

You can refer to detailed information in the [Chaindata change](https://github.com/klaytn/klaytn-docs/blob/main/docs/operation-guide/chaindata-change/README.md)