zookeeper详解（三）

青旅半醒 2022-12-24 06:58 92阅读 0赞

# 一、zookeeper集群部署 #

## 1.算法 ##

### ①2PC（two-phase commit） ###

两阶段提交 ====》 第一阶段 prepare 准备  第二阶段 commit 提交

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM4Mzc3MTkw_size_16_color_FFFFFF_t_70][]

### ②3PC(three-phase commit) ###

三阶段提交 ====》 第一阶段 canCommit 询问

第二阶段 preCommit 准备

第三阶段 docCommit 提交

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM4Mzc3MTkw_size_16_color_FFFFFF_t_70 1][]

### ③Paxos算法 ###

宗旨：少数服从多数规则、角色轮换避免单点故障。

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM4Mzc3MTkw_size_16_color_FFFFFF_t_70 2][]

说明：zk保证集群部署==》数据一致性的算法名称为zab。与Paxos算法类型。

## 2.集群部署 ##

zk集群角色

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM4Mzc3MTkw_size_16_color_FFFFFF_t_70 3][]

zk集群配置

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM4Mzc3MTkw_size_16_color_FFFFFF_t_70 4][]

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM4Mzc3MTkw_size_16_color_FFFFFF_t_70 5][]

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM4Mzc3MTkw_size_16_color_FFFFFF_t_70 6][]

启动===》**启动方式和正常方式启动一样**

![20201127163546690.png][]

可以使用 ./zkServer.sh status 来查看当前zk启动情况。（说明：要在大多数zk服务器启动的情况下，status命令才能看出是否启动成功。）

启动成功效果图。

![20201127164318172.png][]

## 3.zk消息广播与奔溃恢复 ##

消息广播

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM4Mzc3MTkw_size_16_color_FFFFFF_t_70 7][]

奔溃恢复

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM4Mzc3MTkw_size_16_color_FFFFFF_t_70 8][]

## 3.zk客户端连接 ##

客户端的连接

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM4Mzc3MTkw_size_16_color_FFFFFF_t_70 9][]

## 4.问题汇总 ##

①重启zk的中的mode:leader角色,重启后会成为follower

②三台挂掉两台，zk集群就不能用了。（能使用的前提是：绝大数存活）===》类推：七台挂掉四台zk集群就不能用了。

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[20201127163546690.png]: https://img-blog.csdnimg.cn/20201127163546690.png
[20201127164318172.png]: https://img-blog.csdnimg.cn/20201127164318172.png
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