November 2021
Intermediate to advanced
410 pages
12h 1m
Chinese
Content preview from MongoDB权威指南（第3版）
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189
第 10章
创建副本集
本章介绍
MongoDB
的高可用系统：副本集。本章主要内容如下：
•
什么是副本集；
•
如何创建副本集；
•
副本集成员有哪些可用的配置项。
10.1
复制简介
从第
1
章开始，我们就一直在使用单机服务器，一个单独的
mongod
服务器端进程。这是
容易上手的简单方法，但在生产环境中运行风险会很高。如果服务器崩溃或不可访问怎么
办？那么数据库将至少有一段时间不可用。如果硬件存在问题，则可能必须将数据移至另
一台机器上。在最坏的情况下，磁盘或网络问题可能会导致数据损坏或不可访问。
复制是将数据的相同副本保留在多台服务器上的一种方法，建议将其用于所有生产部署
中。即使一台或多台服务器停止运行，使用复制功能也可以确保应用程序正常运行和数据
安全。
在
MongoDB
中
，创建
副本集
（
replica set
）后就可以使用复制功能了。副本集是一组服
务器，其中一个是用于处理写操作的
主节点
（
primary
）
，还有多个用于保存主节点的数
据副本的
从节点
（
secondary
）
。如果主节点崩溃了，则从节点会从其中选取出一个新的
主节点。
如果使用复制功能时有一台服务器停止运行了，那么仍然可以从副本集中的其他服务器访
问数据。如果服务器上的数据已损坏或无法访问，则可以从副本集中的其他成员中创建一
份新的数据副本。
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