Private Cloud (Internal Cloud)
- Organizations build and manage their own private cloud infrastructure within their data center.
- They purchase, install, and maintain their own servers, storage,
and networking equipment.
- All resources are dedicated exclusively to the organization—no sharing with other
customers.
- High initial cost for equipment and setup, but no ongoing
pay-as-you-go or metered costs after deployment.
- Provides full control over security, compliance, and
customization.
- Ideal for organizations with strict data privacy or regulatory
requirements.
Public Cloud (External Cloud)
- Organizations use cloud services provided by third-party vendors (e.g., Amazon Web Services
(AWS), Microsoft Azure, Rackspace).
- No upfront hardware costs—users pay for resources as they use them.
- Resources are shared (multi-tenancy) among multiple customers, but data remains
isolated.
- Customers share the same CPUs, storage drives, and network
infrastructure.
- Pricing models include:
- Metered utilization: Pay based on actual usage (e.g.,
ingress/egress traffic, storage, compute
time).
- Fixed-rate pricing: Pay a set fee for a defined amount of resources (e.g.,
2GB storage/month).
Cost Considerations
- Private Cloud: High initial investment but predictable long-term costs.
- Public Cloud: Lower upfront costs but variable expenses based on usage.
- Metered vs. Non-Metered Billing:
- Metered: Costs fluctuate based on ingress traffic (data
uploaded) and egress traffic (data downloaded).
- Non-Metered: Fixed price for a set resource limit (e.g., storage
capacity).
- Organizations must evaluate usage patterns, budget, and
scalability needs when choosing a model.
Key Cloud Characteristics
- Elasticity: Ability to scale up (increase resources) or
scale down (decrease resources) instantly based on demand.
- High Availability: Redundant systems across multiple data centers
ensure uptime even during failures.
- Global Reach: Data can be automatically synchronized across
regions for faster access and disaster recovery.
- Multi-Tenancy: Multiple customers share the same infrastructure while maintaining
data isolation and security.