> For the complete documentation index, see [llms.txt](https://dev7days.gitbook.io/dev7days/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://dev7days.gitbook.io/dev7days/kubernetes/kubernetes-architecture/etcd.md).

# ETCD

Describe what is ETCD

It is a database that store the data of container and the data of cluster such as `Node` , `Pod`, `Config Map,` `Secret`,  `Account` , `Role` and etc with key-value format.\
\
**The Advantage of Key-value DB:**\
\
Example:

| ID | Name |
| -- | ---- |
| 1  | Bob  |
| 2  | Sam  |
| 3  | Tony |

If you want to add new column in Table it will not affect to existing record in table <br>

| ID | Name |
| -- | ---- |
| 1  | Bob  |
| 2  | Sam  |
| 3  | Tony |

| ID | Name | Age |
| -- | ---- | --- |
| 4  | Jane | 20  |

But If we use relational DB every record in table will need to determine the `Age` value\ <br>

{% hint style="warning" %}
**Noted:**

If you setup cluster manually , you need to download `ETCD binary file` and install on `Master Node`by yourself. Each `Master Node` will separate ETCD but we are able to configure parameter to sync the data across Node .
{% endhint %}