Distributed systems definition

Definiton
1. collection of independent computers
  1. appear users as a single coherent systems
2. one in which components
  1. are located in a networked computers
    1. communicate, coordinate actions
      1. passing messages
Characteristics
1. concurrency
2. no global clock
3. independent failures
why are chosen?
1. scale
  1. processing
  2. data
    1. big data
      1. continues to grow
      2. applications
        data intensive
2. diversity in application domains
3. collaboration
  1. vs individual computers with limited resources
    1. memory and cache
    2. hard disk drive
      1. capacity
      2. channels
      3. limited bandwidth
    3. processor capacity grows faster than memory capacity (55% vs 7%)
    4. processors
      1. CMP (chip multiprocessors)
        Moore's pace
        even if many cores are placed in a CMP, the challenge is to deliver input data to these cores for processing
4. cost
requeriments
1. programming models and concurrency
  1. problems as parallel process
    1. execute each process in different machines
2. communication
  1. process in differents machines
  2. exchange information
3. sincronization
  1. process
    1. cooperate
    2. synchronize
4. consistency and replication
  1. enhance reability
  2. improve performance
5. fault tolerance
  1. recover for partial failures
6. security
  1. process gets access rights to whom is entitled to
7. virtualization
  1. extend interfaces to another system
    1. reduce diversity or platforms
    2. high degree of
      1. portability
      2. flexibility
challenges
1. heterogeneity, openness, security, scalability, failure handling. concurrency of components, transparency, providing QoS

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	Creado por Mónica Zurita hace alrededor de 8 años