I'm studying for my Associate Architect exam at AWS, and I can't find an explanation for this question. Why Dedicated Host are more expensive than Dedicated Instances? I understand the main differences between the two, it is just that in my brain it doesn't make sense.

我正在AWS学习我的副架构师考试，我找不到对这个问题的解释。为什么专用主机比专用实例更贵？我理解两者之间的主要区别，只是在我的大脑中这是没有意义的。

This is my perspective: if you ask for a dedicated host, you control the entire hardware. CPUs, RAM, Sockets, etc. You can use your own license (BYOL). But if you ask for a Dedicated Instance, the hardware it is still just for you. Your AWS account is still the only one using that hardware. You have less control over it, but even though you are locking down a single piece of hardware just for your purposes.

这是我的观点：如果你要求一台专用主机，你就控制了整个硬件。CPU、RAM、插槽等。您可以使用自己的许可证(BYOL)。但如果你要求一个专用的实例，它的硬件仍然只适合你。您的AWS帐户仍然是唯一使用该硬件的帐户。您对它的控制较少，但即使您只是出于您的目的锁定了单个硬件。

So, why dedicated hosts are more expensive than dedicated instances, if after all, in either case, you "own" the hardware? Again, in either case, AWS won't be able to use that hardware for something else.

那么，为什么专用主机比专用实例更贵呢？毕竟，在这两种情况下，您都“拥有”硬件。同样，无论是哪种情况，AWS都不能将该硬件用于其他用途。

you are locking down a single piece of hardware just for your purposes.

Dedicated Instance does not work like this. Your instance runs on some dedicated hardware. Its not lockdown to you. If you stop/start instance, you can get some other hardware somewhere else. Basically, the hardware is "yours" (you are not sharing it with others) for the time your instance is running. You stop/start it, you may get different physical machine later on (maybe older, maybe newer, maybe its specs will be a bit different), and so on. So your instance is moved around on different physical servers - whichever is not occupied by others at the time.

专用实例不是这样工作的。您的实例在一些专用硬件上运行。对你来说这不是禁闭。如果您停止/启动实例，您可以在其他地方获得一些其他硬件。基本上，在您的实例运行期间，硬件是“您的”(您不能与其他人共享)。您停止/启动它，以后可能会得到不同的物理机(可能更旧，也可能更新，可能它的规格会有一点不同)，等等。因此，您的实例在不同的物理服务器上移动--只要当时没有被其他服务器占用。

With Dedicated Host the physical server is basically yours. It does not change, it's always the same physical machine for as long as you are paying.

使用专用主机，物理服务器基本上就是您的了。它不会改变，只要你付钱，它总是相同的物理机器。

Dedicated Host

专用主机

As soon as you 'allocate' a Dedicated Host, you start paying for that whole host.

一旦你“分配”了一台专用主机，你就开始为整个主机付费。

A host computer is very big. In fact, it is the size of the largest instance of the selected family, but can be divided-up into smaller instances of the same family. ("You can run any number of instances up to the core capacity associated with the host.")

主机非常大。实际上，它是选定族的最大实例的大小，但可以拆分为同一族的较小实例。(“您可以运行任意数量的实例，直到达到与主机关联的核心容量。”)

Any instances that run on that Host are not charged, since you are already being billed for the Host.

在该主机上运行的任何实例都不会收费，因为您已经为该主机付费。

That is why a Dedicated Host is more expensive than a Dedicated Instance -- the charge is for the whole host.

这就是为什么专用主机比专用实例更贵的原因--费用是针对整个主机的。

Dedicated Instance

专用实例

"Dedicated Instances are Amazon EC2 instances that run in a virtual private cloud (VPC) on hardware that's dedicated to a single customer... Dedicated Instances may share hardware with other instances from the same AWS account that are not Dedicated Instances."

“专用实例是指在单个客户专用硬件上的虚拟私有云(VPC)中运行的Amazon EC2实例……专用实例可能会与来自同一AWS帐户的其他非专用实例共享硬件。”

This means that no other AWS Account will run an instance on the same Host, but other instances (both dedicated and non-dedicated) from the same AWS Account might run on the same Host.

这意味着任何其他AWS帐户都不会在同一主机上运行实例，但来自同一AWS帐户的其他实例(专用和非专用)可以在同一主机上运行。

Billing is per-instance, with a cost approximately 10% more than the normal instance charge (but no extra charge if it is the largest instance in the family, since it requires the whole host anyway).

按实例计费，费用比正常实例费用高出约10%(但如果是系列中最大的实例，则不会额外收费，因为它无论如何都需要整个主机)。

1. Normal EC2 instance: run on shared hardward where resources like CPU, memory, and network are shared among multiple instances running on the same physical host


2. Dedicated instance: your instance use its own CPU, memory, network, not sharing those resourse with any other instance. Just like you're hiring a small laptop. But if you stop/restart that laptop, next time, you're hiring another laptop.


3. Dedicated hosts: Similar to dedicated instance, but guess what, that laptop is yours, forever, as long as you pay the bill. You stop/restart that laptop, next time you still boot on the same laptop. But usually this laptop is huge, and the price is a lot more expensive

In simple terms:

简单来说：

Dedicated Instance: The physical machine or underlying hardware is reserved for use for the whole account. You can have instances for different purposes on this hardware.

专用实例：预留物理机或底层硬件供全账号使用。您可以在此硬件上拥有用于不同目的的实例。

Dedicated Host: The physical machine or the underlying hardware is reserved for "Single Use" only, eg. a certain application. Thus the physical machine may not be entirely used.

专用主机：物理机或底层硬件仅预留给“单机使用”，例如。某个应用程序。因此，物理机可能不会被完全使用。

The reason why dedicated host maybe more expensive is because you are reserving more resources without actually using them. I think it would make sense when you are aiming for compliance requirements.

专用主机可能更昂贵的原因是因为您保留了更多的资源而实际上没有使用它们。我认为，当你的目标是合规性要求时，这是有意义的。

Think of dedicated hosts for licensing use cases:
Where I want to bring in a license that I already have in my on-prime instance.

考虑将专用主机用于许可使用案例：我希望引入我已在主要实例中拥有的许可证。