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Centralized vs distributed; design issues

Short answer

Centralized system has one central computer with single control and single point of failure; distributed system has independent networked nodes with partial failures and better scalability. Design issues include transparency, communication, naming, process and resource management, consistency and replication, synchronization, fault tolerance, scalability, security, and heterogeneity.

Differentiate between centralized and distributed system. Explain the design issues related to distributed system.

Centralized versus distributed system

PointCentralized systemDistributed system
NodesOne central computer, users use terminalsMany independent computers on a network
ControlSingle point of controlControl and data are spread over nodes
FailureSingle point of failure; whole system stopsPartial failure; remaining nodes continue
ScalabilityLimited by the central machineGrows by adding nodes
CostCostly mainframeCheaper commodity machines
Resource sharingLocal onlyAcross the network
Response timeFalls when the load growsBetter through load sharing
Clock and memoryShared memory and one clockNo shared memory, no global clock
Security and managementEasierHarder
ExampleMainframe with terminalsWeb, cloud

Design issues

  1. Transparency: what to hide (access, location, replication, failure...) and at what cost.
  2. Communication: choice of message passing, RPC, RMI, group communication and protocols.
  3. Naming: unique, location independent names and an efficient name service (DNS).
  4. Process and resource management: scheduling, load balancing, thread use, migration.
  5. Consistency and replication: keep copies consistent while providing speed.
  6. Synchronisation and time: no global clock; need logical clocks, mutual exclusion and election.
  7. Fault tolerance: detection, masking and recovery.
  8. Scalability and performance: avoid bottlenecks, use caching.
  9. Security: authentication, authorisation and secure channels.
  10. Heterogeneity and openness: standard interfaces, middleware.

✓ Answer checked by Claude Opus 5.5 (high effort)

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