Basics of cloud

Servers and Data Centers

• Server: A computer that provides data or services to clients over a network.
  • Types of servers include:
    • Web Server: Hosts websites and serves web pages to users.
    • Database Server: Manages and serves databases for applications.
    • Mail Server: Handles email delivery and management.
• Data Centers:
  • Definition: Secure facilities hosting servers, networks, and storage devices.
  • Features: Climate control, power supplies, and physical security ensure optimal conditions.
  • Ownership Models:
    • On-premises Data Centers: Managed by organizations, involving high costs for hardware, software, facilities, and staffing.
    • Cloud Model: Providers (e.g., AWS) manage data centers, offering resources on a pay-as-you-go basis.

Virtual Machines (VMs)

• Definition: Software-based emulation of a physical computer.
  • Host: Physical computer running the VMs.
  • Hypervisor: Software layer managing resource allocation (CPU, memory, disk, network) for VMs.
  • Multiple VMs: Can run on a single host, each with its own OS and applications.

Benefits of VMs:

1. Cost Savings: Reduce hardware costs by running multiple VMs on one physical machine.
2. Efficiency: Improve resource utilization, reducing waste from underused servers.
3. Reusability and Portability: VM images can be cloned and moved easily across hosts.

Cloud and VMs:

• VMs are the building blocks of cloud computing.
• Services like Amazon EC2 let users create and manage VMs in a scalable, pay-as-you-go model.

SDLC Phases

1. Plan: Define project goals, resources, and a roadmap to guide development.
2. Analyze: Collect and document detailed software requirements in an SRS document.
3. Design: Create a technical blueprint and specify architectures in a design document.
4. Develop: Write the code to build the software according to the design specifications.
5. Test: Verify software functionality, identify defects, and ensure it meets requirements.
6. Implement: Deploy the application in a production environment for end-user access.
7. Maintain: Monitor, update, and enhance the software to meet evolving needs.