Cloud Introduction : Cheat Sheet

3 Cloud Deployment Models  

1. Private Cloud

Dedicated data center for an organization hosted over internet.

2. Public Cloud

Public availability is a key difference between public and private clouds.

3. Hybrid Cloud

Users can flexibly choose which services to keep in public cloud and which to deploy to their private cloud infrastructure.

Public Cloud	Private Cloud	Hybrid Cloud
No capital expenditures to scale up	Organizations have complete control over resources and security	Provides the most flexibility
Applications can be quickly provisioned and deprovisioned	Data is not collocated with other organizations’ data	Organizations determine where to run their applications
Organizations pay only for what they use	Hardware must be purchased for startup and maintenance	Organizations control security, compliance, or legal requirements
Organizations don’t have complete control over resources and security	Organizations are responsible for hardware maintenance and updates

A fourth, and increasingly likely scenario is a multi-cloud scenario. In a multi-cloud scenario, you use multiple public cloud providers. 

Key Characteristics

1. Scalability :  

Vertical Scaling : CPU, Memory, Storage

Horizontal Scaling :  instances of Resources or Nodes

2. Elasticity : 

Ability to Scale Dynamically - Auto Scale feature

3, Agility 

Ability to react quickly. (Ability to allocate and deallocate resources quickly)

In Cloud allocating resources might take time in seconds or minutes but on premises it might take days or weeks.

4. Fault Tolerance 

Remain up and running during component and service failures.

5. Disaster Recovery

Disaster is a serious disruption of services caused by natural or human induces causes. Disaster recovery is the ability to recover from an event that has taken down the service. (Disaster).Achieved by replication. 

6. High Availability 

Availability is a measure of system uptime for users / services. High availability is the ability to keep services running for extended periods of time with very little down time.

Consumption Based Model : 

When comparing IT infrastructure models, there are two types of expenses to consider. Capital expenditure (CapEx) and operational expenditure (OpEx).

CapEx is typically a one-time, up-front expenditure to purchase or secure tangible resources.

In contrast, OpEx is spending money on services or products over time.

This consumption-based model has many benefits, including:

• No upfront costs.
• No need to purchase and manage costly infrastructure that users might not use to its fullest potential.
• The ability to pay for more resources when they're needed.
• The ability to stop paying for resources that are no longer needed.

Cloud Service Models : IAAS vs PAAS vs SAAS

Reference : https://marczak.io/az-900/#navigation