Discuss in detail about distributed system models
Answer:-
Distributed System Models
Distributed computing systems are built over a large number of autonomous computer nodes that are connected via SANs, LANs, or WANs. These systems are highly scalable and support massive web-scale connectivity. Based on architecture, functionality, and application domains, distributed systems are broadly classified into four models:
1. Cluster Computing Model
- Definition: A cluster is a group of loosely coupled, interconnected computers that work together as a single unified computing resource.
- Architecture: Clusters use low-latency, high-bandwidth interconnection networks (LAN/SAN) and are often built using commodity hardware.
- Key Features:
- High-performance computing
- Middleware for job management and load balancing
- Can be used for both sequential and parallel applications
- Challenges:
- Achieving a single-system image (SSI)
- Fault tolerance
- Efficient resource sharing
2. Grid Computing Model
- Definition: Grid computing allows distributed resources (hardware, software, data) from multiple administrative domains to be shared to solve large-scale problems.
- Architecture: Grids are geographically distributed across networks (LAN, WAN, Internet) and combine resources like clusters, servers, and databases.
- Key Features:
- Supports distributed supercomputing and virtual organizations
- Enables large-scale scientific and engineering applications
- Challenges:
- Middleware standardization
- Resource discovery and scheduling
- Security and administrative policies
3. Peer-to-Peer (P2P) Computing Model
- Definition: In a P2P system, each node (peer) acts both as a client and server, without centralized coordination.
- Architecture:
- Ad hoc physical network
- Logical overlay network (structured or unstructured)
- Key Features:
- File sharing, collaboration, distributed computing
- Self-organizing and scalable
- Challenges:
- Data integrity, routing, trust management
- Vulnerable to security threats and piracy
4. Cloud Computing Model
- Definition: Cloud computing provides on-demand access to virtualized computing resources over the Internet.
- Architecture: Based on virtualization of hardware and software resources across large-scale data centers.
- Service Models:
- IaaS: Infrastructure as a Service
- PaaS: Platform as a Service
- SaaS: Software as a Service
- Deployment Models: Public, Private, Hybrid, Managed
- Key Features:
- Elasticity, scalability, cost-efficiency
- Supports multiple applications simultaneously
- Challenges:
- Security, data privacy, SLA management
