Exam Review Flashcards
High Availability
The ability of the application to continue running in a healthy state, without significant downtime. By “healthy state,” we mean the application is responsive, and users can connect to the application and interact with it.
Scalability
Increase or decrease the resources and services used based on the demand or workload at any given time. Vertical Scaling (aka “scaling up) - add more resources to existing servers. Horizontal Scaling (aka “scaling out) - add more servers.
Vertical Scaling (aka “scaling up”)
The process of adding resources to increase the power of an existing server (e.g. adding a faster CPU, additional CPUs, more memory).
Horizontal Scaling (aka “scaling out”)
The process of adding more servers that function together as one unit (e.g. adding more servers).
Agility
Cloud agility is the ability to rapidly change an IT infrastructure in order to adapt to the evolving needs of the business (e.g. if your service peaks one month, you can scale to demand and pay a larger bill for the month. If the following month the demand drops, you can reduce the used resources and be charged less).
Fault Tolerance
Redundancy is often built into cloud services architecture so if one component fails, a backup component takes its place. This is referred to as fault tolerance and it ensures that your customers aren’t impacted when an unexpected accident occurs.
Disaster Recovery
The ability to recover from rare but major incidents: non-transient, wide-scale failures, such as service disruption that affects an entire region. Disaster recovery includes data backup and archiving, and may include manual intervention, such as restoring a database from backup.
Economies of Scale
Economies of scale is the ability to do things more efficiently or at a lower-cost per unit when operating at a larger scale (e.g. the ability to acquire hardware at a lower cost than if a single user or smaller business were purchasing it, cloud providers can also make deals with local governments and utilities to get tax savings, lower pricing on power, cooling, and high-speed network connectivity between sites).
Capital Expenditure (CapEx)
CapEx is the spending of money on physical infrastructure up front, and then deducting that expense from your tax bill over time. CapEx is an upfront cost, which has a value that reduces over time.
Operational Expenditure (OpEx)
OpEx is spending money on services or products now and being billed for them now. You can deduct this expense from your tax bill in the same year. There is no upfront cost, you pay for a service or product as you use it.
Infrastructure-as-a-Service (IaaS) (shared responsibility model)
Infrastructure as a Service is the most flexible category of cloud services. It aims to give you complete control over the hardware that runs your application (IT infrastructure servers and virtual machines (VMs), storage, networks, and operating systems). Instead of buying hardware, with IaaS, you rent it. It’s an instant computing infrastructure, provisioned and managed over the internet.
Platform-as-a-Service (PaaS)
PaaS provides an environment for building, testing, and deploying software applications. The goal of PaaS is to help you create an application quickly without managing the underlying infrastructure. For example, when deploying a web application using PaaS, you don’t have to install an operating system, web server, or even system updates. PaaS is a complete development and deployment environment in the cloud.
Software-as-a-Service (SaaS)
SaaS is software that is centrally hosted and managed for the end customer. It is usually based on an architecture where one version of the application is used for all customers, and licensed through a monthly or annual subscription. Office 365, Skype, and Dynamics CRM Online are perfect examples of SaaS software.
Describe the responsibilities of the different service models.
IaaS
User -
Purchase, installation, configuration, and management of their own software operating systems, middleware, and applications.
Cloud Provider - Responsible for ensuring that the underlying cloud infrastructure (such as virtual machines, storage, and networking) is available for the user.
PasS
User - Responsible for the development of their own applications.
Cloud Provider - Responsible for operating system management, and network and service configuration.
SaaS
User -
Users just use the application software; they are not responsible for any maintenance or management of that software.
Cloud Provider -
The cloud provider is responsible for the provision, management, and maintenance of the application software.
Public Cloud
This is the most common deployment model. In this case, you have no local hardware to manage or keep up-to-date – everything runs on your cloud provider’s hardware.
Private Cloud
In a private cloud, you create a cloud environment in your own datacenter and provide self-service access to compute resources to users in your organization.
Hybrid Cloud
A hybrid cloud combines public and private clouds, allowing you to run your applications in the most appropriate location.
Advantages and Disadvantages of Cloud Models
Public
Advantages -
+ High Scalability/Agility
+ PAYG (No CapEx, OpEx model)
+ Not responsible for hardware maintenance
+ Minimal technical knowledge required
Disadvantages -
- May not be able to meet specific security requirements
- May not be able to meet specific compliance requirements
- You don’t own the hardware and may not be able to manage them as you wish
Private Advantages - \+ You have complete control \+ Can meet strict security and compliance requirements Disadvantages - - Upfront CapEx costs - Owning equipment limits agility to scale - Requires high technical knowledge
Hybrid
Advantages - + Advantages of both Public and Private
Disadvantages -
- Can be more expensive than selecting one deployment model
- Can be more complicated to set up and manage
Benefits of Cloud Computing
• Cost Effective:Pay-as-you-go, consumption-based pricing model. Rather than paying for hardware up-front, you rent hardware and pay for the resources that you use.
• Scalable:Increase or decrease the resources and services used based on the demand or workload at any given time.
• Elastic:Automatically add or remove resources based on demand.
• Current:Computer hardware and software is automatically maintained by the cloud provider.
• Reliable:Cloud providers offer data backup, disaster recovery, and data replication services. Redundancy is often built into cloud services architecture so if one component fails, a backup component takes its place.
• Global:Cloud providers have fully-redundant datacenters located in various regions all over the globe (performance, redundancy, compliance).
Secure:Cloud providers offer a broad set of policies, technologies, controls, and expert technical skills that can provide better security than most organizations can otherwise achieve.
Geography
An Azure geography is a discrete market typically containing two or more regions that preserve data residency and compliance boundaries.
Current: Americas, Europe, Asia Pacific, Middle East and Africa
Region
A region is a geographical area on the planet containing at least one, but potentially multiple datacenters that are nearby and networked together with a low-latency network.
Example: North Europe, West Europe, Germany North, Germany West Central
Availability Zone
Availability Zones are physically separate datacenters within an Azure region. Each Availability Zone is made up of one or more datacenters equipped with independent power, cooling, and networking.
Availability Sets
Availability Sets comprise of update and fault domains. Update Domain: When a maintenance event occurs, the update is sequenced through update domains. Fault Domain: Fault domains provide for the physical separation of a workload across different hardware in the datacenter.
Hierarchy
Geography > Region > Availability Zone > Availability Set > Fault Domain/Update Domain
