# Chaindata Change

💡 THIS GUIDE IS BASED ON Amazon Linux 2

## CN Node **Migration STEP**

### Create new disk

1. Preparing new disk (3,500GB disk) or creating new path on the current disk (It must have 3,500GB available.)

💡 Assuming that the new path is \`/var/kcnd2\`

#### Option 1 - New disk (more than 2500GB)

1. Attach the disk to EC2 and run the command below

```bash
$ lsblk
NAME          MAJ:MIN RM  SIZE RO TYPE MOUNTPOINT
nvme2n1       259:0    0  3500G  0 disk **# New Disk**
nvme1n1       259:0    0  4000G  0 disk /var/kcnd
nvme0n1       259:2    0    8G  0 disk
├─nvme0n1p1   259:3    0    8G  0 part /
└─nvme0n1p128 259:4    0    1M  0 part
```

2. Mount it following the process below

```bash
$ sudo e2fsck -f /dev/nvme2n1
$ sudo mkfs -t ext4 /dev/nvme2n1
$ sudo mkdir /var/kcnd2
$ sudo mount /dev/nvme2n1 /var/kcnd2
$ sudo mkdir /var/kcnd2/data
$ sudo mkdir /var/kcnd2/log
```

#### Option 2 - Current Disk (not recommended)

1. Create New Folder

```bash
$ sudo mkdir /var/kcnd2/data
$ sudo mkdir /var/kcnd2/log
```

### Download the latest chaindata

Download Chain Data to the data of the new Klaytn Data DIR. (You can check the details on Chain Data in <https://packages.klaytn.net/cypress/chaindata/>)

1. Download with the following command

```bash
# (Option 1: recommended) curl 
$ curl -o klaytn-cypress-chaindata-2021???????????.tar.gz "https://s3.ap-northeast-2.amazonaws.com/klaytn-chaindata/cypress/klaytn-cypress-chaindata-2021???????????.tar.gz"

# (Option 2) aws s3 command
$ aws s3 cp s3://klaytn-chaindata/cypress/klaytn-cypress-chaindata-2021???????????.tar.gz klaytn-cypress-chaindata-20211113011111.tar.gz 

# (Option 3) axel (need to install axel)
sudo amazon-linux-extras install epel -y
sudo yum install axel pigz
$ axel -n8 https://s3.ap-northeast-2.amazonaws.com/klaytn-chaindata/cypress/klaytn-cypress-chaindata-2021???????????.tar.gz
```

2. Decompress

```bash
# (Option 1: recommended) tar
$ tar -xvf klaytn-cypress-chaindata-2021???????????.tar.gz

# (Option 2) pigz (need to isntall pigz)
$ tar -I pigz -xvf klaytn-cypress-chaindata-2021???????????.tar.gz
```

## Configure DATA\_DIR & LOG\_DIR

### Option 1 - Swap the old & new path

🚨 TBD

1. Stop klaytn daemon process before swap

   1. ***IMPORTANT*** Remove CN node in Klaytn council if the node type is CN

   💡 You can get packages for EN in the [Startup the CN](/content/installation-guide/deployment/core-cell/installation-guide/consensus-node-setup/startup-the-cn.md).
2. Swap the old and new path

   1. New Disk

      ```bash
      umount /var/kcnd # old path
      umount /var/kcnd2 # new path
      mount /dev/nvme2n1 /var/kcnd
      ```

   💡 These commands should be executed with the appropriate privileges.

   2. Current Disk

      ```bash
      sudo mv /var/kcnd /var/kcnd_old # old_path
      sudo mv /var/kcnd2 /var/kcnd # new path
      ```
3. (Optional) Delete the old path if it is not required anymore

### Option 2 - Update DATA\_DIR & LOG\_DIR in klaytn config file

1. Klaytn DIR Path Change
   * Option 1 - New disk
     * Change `fstab` value from old disk to new disk
   * Option 2 - Current disk
     * change the DIR Path from `kcnd.conf`

## Restart Process(or Reboot Instance)

💡 If reboot is required to add an additional disk, reboot the instance.

1. ***IMPORTANT*** Remove CN node in Klaytn council if the node type is CN
2. Restart process or reboot instance


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://archive-docs.klaytn.foundation/content/operation-guide/chaindata-change.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.