Cloud and Scalable Computing

Why Cloud?

Uneven Utilizations by nature

• Day of the week and hours of the day: Web surfing
• Season of the year: Christmas e-gift cards
• Adhoc usage: One-off computation jobs/testing

Economies of scale

Cloud Benefits: on-demand + sharing

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Cloud Types - Cloud Service Models

• Infrastructure-as-a-Service (IaaS)
• Platform-as-a-Service (PaaS)
• Software-as-a-Service (SaaS)

What service model the following offer (SaaS, PaaS, IaaS)?

• Salesforce.com - SaaS
• Amazon Web Services (AWS) Elastic Beanstalk, Azure App Service - Paas
• AWS Elastic Compute Cloud (EC2) - IaaS

What other X-as-a-Service have you heard of?

• Model aaS
• Function aaS
• Container aaS

Ownership Models

• Public Cloud
• Private Cloud
• Hybrid Cloud - Resources from 2+ computing environments
• Community Cloud - Group of consumers having the same conern

Scaling Up vs. Scaling Out

• Scale-up (vertically): more resources for a single node: More expensive for supercomputer (less cost-effective)
• Scale-out (horizontally): more nodes
  • A farm of cheaper instances well-networked (high throughput)
  • Application distributable in individual instances

Design Considerations

• Scalability and Elasticity
  • Auto-scaling allows on-demand instances/node creation/removal
  • Possibly based on metrics: CPU, memory, disk I/O, network I/O...
• Fault Tolerance for Availability
  • Automated recovery for EC2 instances when some of them die
  • Automated backups for storage
• Software Deployability
  • Easy to deploy; and create a new environment to test out changes
  • Integrated with GIT for systematic versioning control