Читать книгу CompTIA Cloud+ Study Guide - Ben Piper, David Higby Clinton - Страница 62

Before making plans to migrate anything to the cloud, it's important to decide whether you want to use the IaaS, PaaS, or SaaS model, or any combination thereof. The model you use will determine the specific cloud building blocks you'll have to put together. As you already know, IaaS leaves much of the work in your hands, making migrations more flexible but more complicated. On the other end of the spectrum, the SaaS model makes migrations quicker and easier, but at the cost of giving up control over the infrastructure.

Once you decide on the model, identify what services and capabilities are available in the cloud that fit your needs and requirements. As service providers have expanded their offerings and capabilities, understanding all your options has become almost overwhelming. Some of the largest public cloud companies have more than a thousand objects and services to choose from, with more being added regularly.

To give you an idea of the plethora of options, let's start with the IaaS model. When it comes to virtual servers, there are a variety of prebuilt OSs to choose from. On the virtual hardware side, you can choose CPU and GPU power, memory, storage volumes, and network I/O. On the network side, you have load balancing, DNS and DHCP services, routing, firewalls, network address translation (NAT), and more. For storage, most cloud companies offer block, object, and file storage.

When it comes to PaaS and SaaS models, your options are naturally more limited because the provider takes on more responsibility for the back-end infrastructure. However, it's not unusual for a provider to offer different services that seem to be very similar to one another. For example, cloud providers offer a variety of managed database services for different types of databases. Likewise, they may offer messaging or email services that are compatible with different on-prem solutions. And of course, PaaS services and tools for developing and deploying applications are limited only by the vast number of programming languages out there.