The evolution of Cloud Technology. In this lesson, our learning objective is to be able to describe the evolution of Cloud Technology. The stages of cloud evolution we're going to discuss are the Simple Network, a Virtual Server Network, the Private Cloud, the Public Cloud and a Hybrid Cloud. We started off with simple networks, that's where business had one or many servers and all the machines in their business were connected to each other using cables in a local network. Its on premises, which means, it's on your property. Each server is a physical server. So any time you need to add an extra server, you need to go buy another piece of equipment, and it doesn't give you a lot of flexibility or reliability, because what happens is, if one of the servers crashes, or some of the hardware goes bad or the power goes out on one of the servers, whatever it's doing is lost. And finally, you end up with high fixed costs, because you have to buy the machines up front even though you're going to continue to use them over the next three to five years. For that reason, we eventually moved to the network of virtual servers. Now, this is still on premises, but what we're doing now, in this case, is every physical server, every piece of hardware has multiple virtual servers running on it, which means, that we end up having some additional flexibility and reliability. If one of the virtual servers crashes, because it's running inside of software on your physical server. You can configure that software so that it automatically reboots the virtual machine, which because it's a virtual machine can happen very, very quickly. So some of these machines would crash and come back within 30 seconds. So that's your reliability. The flexibility comes in, depending on how your infrastructure set up. If you want to add an extra virtual server, as long as you still have space on one of your physical servers, you can add that without having to buy more hardware. So instead of it taking one to two weeks for you to add an extra server because you'd have to provision some hardware, buy it, get it delivered, install it and what have you, with a virtual server, you can just go onto one of your existing physical machines, tell it, I want you to run another virtual server with these resources and you can have it up in less than 20 minutes. And because of that, you end up with lower fixed costs than the simple network. However, we wanted to be able to have more flexibility and reliability, and even lower fixed costs, which brings us to the Private Cloud. Now, the Private Cloud is still on premises. But now, instead of having each physical server standing on its own, you tie all of your physical service together into something called a cluster. So they're grouped, and they host all of your virtual machines together. So if you have 10 physical servers and one of them fails, the amount of resources available to you drops by 10%. But the system accounts for that fact, and it moves things around, and generally speaking, can keep things running without your users even noticing anything has happened, which means that you have high reliability. Now, as far as flexibility is concerned, you can easily increase the resources of one of your virtual machines or even the number of your virtual machines without making huge purchases, or waiting for things to get delivered, because your were operating it on this, what we're calling a Cloud, that you're running inside of your business. So you are able to lower your fixed costs over what it would be of buying a bunch of individual servers for each individual purpose. Now, running a virtual Cloud like this requires knowledge of advanced virtual infrastructure. So there is an additional cost in labor over having just a network of virtual servers. But the solution to that is to move to the Public Cloud. Now, the Public Cloud is off premises, it's not on your business's property. And the virtual machines are all hosted in the remote Cloud. So you have all the benefits of the Private Cloud except the Public Cloud is even bigger. So you still have higher flexibility, you still have high reliability, and now, you don't just have lower fixed costs, you have no fixed cost. It is pay as you go, so you can go to Amazon, or Azure, or GCP, Google Cloud Platform, and you can tell them, I want 100 servers for this month, and next month, I don't want any, and you only pay for what you use. And because all of it is handled by the Cloud Provider, you don't have to have personnel on board that have knowledge of advanced virtual infrastructure to run it, because that's the company's problem. Now, sometimes, you want a combination of Public and Private Clouds. So you want to move to the Hybrid Cloud, which is both on and off premises. Your virtual machines are all hosted on the Remote Cloud and/or local servers. It gives you high flexibility and high reliability of being on the Public Cloud, but it also gives you the control of being on a Private Cloud. So you have a pay as you go part, which is in the public, and a fixed cost part, that is in the private. And it requires knowledge of advanced virtual infrastructure, but in some ways, it's the best of both worlds. You're not held hostage to what some external company wants to do if you need to, you can pull everything back. However, you're also not forced to purchase large amount of physical hardware when you need to do drastic expansions, because you have that capability on the Public Cloud to quickly expand. Let's say, if you're running an online application that only is really useful during Halloween. Then in the weeks leading up to Halloween, you could expand drastically, and the day after, you could shrink back down to just using the servers in your Private Cloud. So how do you choose? You want to go with the Public Cloud? If your startup or business that's moving totally to the Cloud, just go ahead and go public, then you can actually get rid of all of that. Built in cost, that fixed cost of having your own on premises servers, your own on premises, server manager, server administrators, all of that. Private Cloud are for businesses that need a Cloud, but also need full control. Also, some companies go with a Private Cloud when they're moving towards the Cloud but they're not quite ready, or not quite have the trust to move to a Public Cloud. So they'll move to a Private Cloud as a first step, then eventually, they'll think about moving to a Public Cloud as their servers get older and they get rid of them. And the Hybrid Cloud is for that combination, it's a business that's using Cloud and needs some control, but they also want the flexibility of being able to grow and shrink. In this lesson, our learning objective was to be able to describe the evolution of Cloud Technology.