系统的可扩展性

什么是系统的可扩展性？

到底什么是可扩展性 ？这年头，作为软件设计架构师如果系统没有可扩展性对外交流时都不好意思。但是

如何 选择可扩展性方案？水平扩展还是垂直扩展？是不是很矛盾呢，本文为你分析可扩展性的真实含义和

实际项目中的取舍。

When asked what they mean by scalability, a lot of people talk about improving

performance, about implementing HA, or even talk about a particular technology

or protocol. Unfortunately, scalability is none of that. Don

’

t get me wrong. You

still need to know all about speed, performance, HA technology, application

platform, network, etc. But that is not the definition of scalability.

每每和别人提及可扩展性的含义时，很多人开始讨论提高性能，实施高可

用性，甚至谈论特定的技术或协议。显然这些并不是可扩展性。不要误会，您

当 然需要了解关于速度，性能，可用性，应用平台，网络等相关的一切，但这

并非可扩展性 的定义。

Scalability, simply, is about doing what you do in a bigger way. Scaling a web

application is all about allowing more people to use your application. If you can

’

t

figure out how to improve performance while scaling out, its okay. And as long as

you can scale to handle larger number of users its ok to have multiple single

points of failures as well.

简单地说，可扩展性就是关于如 何处理更大规模的业务。比如，

Web

应用

程序就是允许更多的人使用你的服务。如果你不能弄清楚如何提高性能的同时

向外扩 展，没关系。只要你能处理更大规模的用户，即使是存在多个单点故障

也没有问题。

There are two key primary ways of scaling web applications which is in practice

today.