# Zookeeper集群搭建

## 集群规划

| 节点  | 主机        | clientPort |
| --- | --------- | ---------- |
| zk1 | hadoop102 | 2181       |
| zk2 | hadoop103 | 2181       |
| zk3 | hadoop104 | 2181       |

## 配置集群

### 1. 配置 zoo.cfg

在每台节点上编辑 `conf/zoo.cfg`：

```properties
dataDir=/opt/module/zookeeper-3.8.X/data
clientPort=2181
tickTime=2000
initLimit=10
syncLimit=5

# 集群配置
server.1=hadoop102:2888:3888
server.2=hadoop103:2888:3888
server.3=hadoop104:2888:3888
```

**端口说明**：

* **2888**：Follower 与 Leader 通信端口
* **3888**：选举 Leader 的端口

### 2. 创建 myid 文件

在每个节点的 `dataDir` 目录下创建 `myid` 文件：

```bash
# 在 hadoop102
echo 1 > /opt/module/zookeeper-3.8.X/data/myid

# 在 hadoop103
echo 2 > /opt/module/zookeeper-3.8.X/data/myid

# 在 hadoop104
echo 3 > /opt/module/zookeeper-3.8.X/data/myid
```

### 3. 启动集群

```bash
# 在每个节点上执行
bin/zkServer.sh start

# 查看状态
bin/zkServer.sh status
```

**预期结果**：

* 一个 Leader
* 两个 Follower

### 4. 验证集群

```bash
# 连接到任一节点
bin/zkCli.sh -server hadoop102:2181

# 创建节点
[zk: hadoop102:2181] create /test "cluster data"

# 在另一节点验证
bin/zkCli.sh -server hadoop103:2181
[zk: hadoop103:2181] get /test
```

## 集群角色

### Leader

* 处理写请求
* 发起投票

### Follower

* 处理读请求
* 参与 Leader 选举投票

### Observer

* 处理读请求
* 不参与投票（仅扩展读性能）

## 选举机制

1. 每个节点启动时都是 LOOKING 状态
2. 发起选举投票
3. 超过半数节点投票给同一节点时，该节点成为 Leader
4. 其他节点成为 Follower

## 总结

ZooKeeper 集群需要至少 3 个节点，推荐奇数节点。集群可以容忍 (N-1)/2 个节点故障。


---

# 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://qiangrens-organization.gitbook.io/qkd90/13zookeeper-xie-tiao-fu-wu/zookeeper-ji-qun-da-jian.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.