Читать книгу CompTIA Cloud+ Study Guide - Ben Piper, David Higby Clinton - Страница 112

 Know that cloud computing is similar in operation to a utility. Cloud computing follows the utilities model where a provider will sell computing resources using an as-needed or as-consumed model. This allows a company or individual to pay for only what they use.

 Know what cloud computing is. Cloud computing is a model for enabling convenient, on-demand network access to a shared pool of configurable computing resources (for example, networks, servers, storage, applications, and services) that can be rapidly provisioned and released with minimal management effort or service provider interaction. This cloud model is composed of five essential characteristics, three service models, and four deployment models.

 Understand the different cloud service models and how to differentiate between them. Cloud service models are characterized by the phrase as a service and are accessed by many types of devices, including web browsers, thin clients, and mobile devices. There are three primary service types. Software as a Service, Infrastructure as a Service, and Platform as a Service are the core service offerings. Many cloud service providers offer more descriptive terms in their marketing and sales offerings, including Communications as a Service, Anything as a Service, and Desktop as a Service. However, all of these newer terms fit into the SaaS, IaaS, or PaaS service model. Study the service models and know the differences among IaaS, PaaS, and SaaS as well as the other service models.

 Know the primary cloud delivery models. The four primary cloud delivery models are public, private, community, and hybrid clouds. Know what each one is and its function. It is critical that you understand the way cloud services are delivered in the market today and what they offer.

 Be able to identify and explain cloud components. Common cloud components include applications, automation, compute, networking, security, and storage.

 Know the cloud shared resource pooling model and how it is used. Resource pooling is when the cloud service provider abstracts its physical compute, storage, and networking resources into a group, or pool. The resources from these pools are dynamically allocated to customers on-demand. Resource pooling hides the underlying physical hardware from the customers in such a way that different customers share the underlying infrastructure while their cloud resources remain isolated from each other.

 Understand cloud performance components. The performance you are able to achieve with your deployment is a combination of the capabilities and architecture of the cloud service provider and how you design and implement your operations. Some metrics that you'll want to consider are bandwidth usage, network latency, storage I/O operations per second (IOPS), and memory utilization.

 Be able to explain how autoscaling works. The ability to automatically and dynamically add additional resources such as storage, CPUs, memory, and even servers is referred to as elasticity. Using autoscaling, this can be done “on the fly” as needed or on a scheduled basis. This allows for cloud consumers to scale up automatically as their workload increases and then have the cloud remove the services after the workload subsides. On-demand cloud services allow the cloud customer to access a self-service portal and instantly create additional servers, storage, processing power, or any other services as required. If the computing workload increases, then additional cloud resources can be created and applied as needed. On-demand allows customers to consume cloud services only as needed and scale back when they are no longer required.

 Know what regions and availability zones are. Large cloud operations partition operations into geographical regions for fault tolerance and to offer localized performance advantages. A region is not a monolithic data center but rather a geographical area of presence. The actual data centers in each region are availability zones. Each region will usually have two or more availability zones for fault tolerance. The AZs are isolated locations within cloud data center regions that public cloud providers originate and operate. Each availability zone is a physically separate data center with its own redundant power and network connections.