在云计算(Cloud Computing)中，尽管这个概念并不新鲜，但在涉及基础设施即服务(Infrastructure as a Service)时却存在很多混乱。云提供商提供的其他两种类型的服务更加清晰。本文尝试与IaaS相关的问题。
什么是基础设施即服务
云(Cloud)计算服务（不是云本身）分为三大类：
- 软件即服务(Software as a Service)：(Software as a Service:)您可以在必要时访问某些软件。想想(Think)备份服务。你有他们的软件，你用它来备份你的文件。当您将文件添加到要备份的文件夹时它会激活，否则它只是躺在那里监视文件夹。该服务是可扩展的，并且可以使用运行所提供软件的不同设备访问备份文件。
- 平台即服务：为(Platform as a Service:)您提供执行特定任务的平台。想象一下(Imagine)电子邮件服务。您有一个可以访问和发送电子邮件的平台。它也是可扩展的——这意味着存储会根据电子邮件的数量和类型而变化。您可以从任何地方访问它。
- 基础设施即服务(Infrastructure as a Service)：IaaS 为企业提供所需的基础设施，以便他们可以构建自己的平台来服务自己和客户。想象一个虚拟服务器。你可以用它做任何事情；服务器的使用方式没有限制；优点是这也是可扩展的——你只需要根据需要使用尽可能多的服务器/调用。它也可以从任何地方访问，而不是内部服务器。
基础架构通常是虚拟化的，以便在硬件由于某种原因出现故障时可以将其从一台服务器转移到另一台服务器。最大(Maximum)的正常运行时间对于为公司及其客户提供尽可能最大的响应至关重要。
阅读(Read)：Microsoft Office 即服务。
使用 IaaS 构建 SaaS 和 PaaS
如果您查看使用它创建其他类型的云产品的可能性，可以更好地理解基础设施即服务。(Service)也就是说，您可以使用IaaS并使用它来创建以后分发给人们的软件。同样的东西在需要时为您提供空间，以便您的SaaS（软件服务）客户可以在线存储他们的数据。
同样，您可以构建一个平台并将其作为服务提供给您的客户。您可以通过租用IaaS(IaaS)提供的设施来做到这一点。它可以节省成本，并允许您随着业务或客户群的增长进行投资。例如，您创建Word、Excel和PowerPoint的在线版本，并为您的用户提供创建文档、协作、发送/接收电子邮件等的平台。最初，您只为最初的几个用户占用一定数量的代币。由于IaaS具有可扩展性，因此您可以随着平台的增长而增加基础架构。
阅读：(Read:) Windows 即服务。
什么都捆绑到 IaaS 中？
以低投资获得更多计算能力！？您可以使用IaaS服务来扩展、缩小甚至开始您的业务。服务提供商将为您提供必要的基础设施，这样您就不必立即在上面投资太多。您可以在需要时执行此操作。
虽然IaaS(IaaS)的基本定义仅限于用于数据中心等计算的虚拟服务器，但许多(Servers)IaaS提供商为您提供数据库、网络和防火墙等虚拟化内置服务，以便您可以直接使用它们 - 无需购买任何东西或编写任何代码刮。但这些都是额外的好处，因此不能被视为基础设施(Infrastructure)即服务(Service)的一部分。
服务器的维护和保持是IaaS提供商的工作。用户负责更新他们可能在基础架构上使用的操作系统和其他软件。这种情况与云服务提供商必须保持其软件更新的平台(Platforms)即服务(Service)和软件即服务不同。(Software)
基础设施(Infrastructure)即服务(Service)示例
截至2016 年11 月 20(November 20)日撰写本文时， Amazon Web Services ( AWS ) 是最常用的IaaS服务。它以非常实惠的价格提供高度的灵活性和良好的售前和售后咨询。微软的(Microsoft)Microsoft Azure服务紧随其后。还有一些其他公司在竞争，但他们甚至没有那么接近。
谷歌有计算(Compute)——与类似的产品相比，不太受欢迎，而且成本有点高，但可以完成工作。假设(Suppose)您需要处理大量会挂起您的机器的数据。你可以去计算(Compute)并完成它。
您同样可以使用Azure来构建应用程序，还可以托管和分发它们。这只是您可以按需使用可扩展基础架构的众多示例之一。您可以使用IaaS（基础架构(Infrastructure)即服务(Service)）来扩展您的数据中心或向全世界提供定制服务。由于购买高端硬件不再是问题，因此可能性是无限的。
Infrastructure as a Service - Definition, Explanation and Examples
Іn Cloud Computing, even though the concept is not much new, there is much confusion when it comes to Infrastructure as a Service. The other two types of services offered by cloud providers are clearer. This article attempts questions related to IaaS.
What is Infrastructure as a Service
Cloud computing services (not the cloud itself) are categorized into three broad categories:
- Software as a Service: You are given access to some software that works as and when necessary. Think of backup service. You have their software and you use it to back up your files. It activates when you add a file to the folders to be backed up and otherwise is just lying there monitoring the folders. The service is scalable and the backed-up files can be accessed using different devices that run the provided software.
- Platform as a Service: You are given a platform to perform particular tasks. Imagine an email service. You have a platform from where you can access and send emails. It too is scalable – meaning the storage varies according to the number and types of emails. And you can access it from anywhere.
- Infrastructure as a Service: IaaS provides the required infrastructure to enterprises so that they can build their own platforms to serve themselves and their customers. Imagine a virtual server. You can do anything with it; there are no restrictions as to how the server should be used; plus points are that this too is scalable – you only use as much server/calls as required. It too can be accessed from anywhere as against the in-house servers.
The infrastructure is generally virtualized so that it can be shifted from one server to another in case the hardware is down for some reason. Maximum uptime is essential so as to provide companies and thereby, their customers with the maximum response possible.
Read: Microsoft Office as a Service.
Build SaaS and PaaS using IaaS
Infrastructure as a Service can be better understood if you look at the possibilities of creating other types of cloud offerings using it. That is, you can go for IaaS and use it to create software that is later distributed to people. The same thing gives you space as and when required so that your SaaS (software service) customers can store their data online.
Likewise, you can build a platform and offer it as a service to your clients. You can do this by hiring facilities that IaaS provides. It saves cost and allows you to invest as your business or client base grows. For example, you create online versions of Word, Excel, and PowerPoint and provide your users with the platform to create documents, collaborate, send/receive emails, etc. Initially, you take up only a token amount for your first few users. Since IaaS is scalable, you can increase the infrastructure as the platform grows.
Read: Windows As A Service.
What all is bundled into IaaS?
More computing power at low investment!? You can use IaaS services to expand, shrink, or even start your business. The service provider will give you the necessary infrastructure so that you don’t have to invest much in it right away. You do it as and when required.
While the basic definition of IaaS is limited to virtual Servers for datacenters etc. computing, many IaaS providers give you databases, networking and firewalls etc. services built into virtualization so that you can use them directly – without having to buy stuff or code anything from scratch. But these are added benefits and as such, cannot be considered part of Infrastructure as a Service.
The maintenance of servers and keeping them up is the work of IaaS providers. Users are responsible for updating OS and other software they may be using over the infrastructure. This case is different from both Platforms as a Service and Software as a service where the cloud service provider has to keep his software updated.
Examples of Infrastructure as a Service
As of writing this article, November 20, 2016, Amazon Web Services (AWS) is the most used IaaS service. It provides high flexibility with good pre and after-sales consultation at highly affordable prices. Microsoft is right behind with its Microsoft Azure service. There are some other companies in the race but they are not even as much as close.
Google has Compute – not much popular and a bit costly compared to similar offerings but gets work done. Suppose you need to process tons of data that would hang your machines. You can go for Compute and get it done.
You can likewise use Azure to not only build apps but also to host and distribute them. It is just one of the many examples you can do using scalable infrastructure on demand. You can use IaaS (Infrastructure as a Service) to extend your datacenters or to make available custom services to the entire world. The possibilities are unlimited as high-end hardware purchases are not an issue anymore.
