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Questions and Answers
What defines a distributed system?
What defines a distributed system?
Which characteristic describes the failure susceptibility of distributed systems?
Which characteristic describes the failure susceptibility of distributed systems?
What does middleware in a distributed system primarily provide?
What does middleware in a distributed system primarily provide?
How does a distributed system ensure availability?
How does a distributed system ensure availability?
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What aspect of distributed systems allows them to easily adapt to increasing workloads?
What aspect of distributed systems allows them to easily adapt to increasing workloads?
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What is a key goal of distributed systems in terms of user interaction?
What is a key goal of distributed systems in terms of user interaction?
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Which characteristic is NOT associated with distributed systems?
Which characteristic is NOT associated with distributed systems?
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What does transparency in a distributed system allow?
What does transparency in a distributed system allow?
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What challenge does distributed systems mainly face regarding data transfer?
What challenge does distributed systems mainly face regarding data transfer?
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What does the goal of interoperability in distributed systems allow?
What does the goal of interoperability in distributed systems allow?
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Which dimension of scalability refers to the distance between nodes in a distributed system?
Which dimension of scalability refers to the distance between nodes in a distributed system?
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What is one of the techniques for scaling mentioned in the content?
What is one of the techniques for scaling mentioned in the content?
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What is a potential issue when a distributed system scales up?
What is a potential issue when a distributed system scales up?
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Which goal of distributed systems allows applications to function without modification when transferring from one system to another?
Which goal of distributed systems allows applications to function without modification when transferring from one system to another?
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What type of system is a decentralized naming service an example of?
What type of system is a decentralized naming service an example of?
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What does caching in a distributed system primarily aim to achieve?
What does caching in a distributed system primarily aim to achieve?
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Why should centralized solutions be avoided in distributed systems?
Why should centralized solutions be avoided in distributed systems?
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What is one way to hide communication latencies in a distributed system?
What is one way to hide communication latencies in a distributed system?
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What does extensibility in a distributed system allow for?
What does extensibility in a distributed system allow for?
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What is the purpose of replication in scaling techniques?
What is the purpose of replication in scaling techniques?
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Which of the following statements about caching is true?
Which of the following statements about caching is true?
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What scaling technique involves spreading parts of a component around different machines?
What scaling technique involves spreading parts of a component around different machines?
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In which scenario is strong consistency particularly crucial?
In which scenario is strong consistency particularly crucial?
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What is a potential downside of using replication as a scaling technique?
What is a potential downside of using replication as a scaling technique?
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Which example demonstrates weak consistency?
Which example demonstrates weak consistency?
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What is a primary goal of hiding communication latencies in scaling techniques?
What is a primary goal of hiding communication latencies in scaling techniques?
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What is the relationship between caching and replication in scaling techniques?
What is the relationship between caching and replication in scaling techniques?
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What does decentralized naming services help achieve in a distributed system?
What does decentralized naming services help achieve in a distributed system?
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Which technique involves making local copies of resources for quicker access?
Which technique involves making local copies of resources for quicker access?
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Study Notes
Distributed Operating Systems
- A distributed system is a collection of independent computers that appears to users as a single, coherent system.
- Characteristics include: prone to failure, limited bandwidth, and latency.
- Organized as middleware that extends over multiple machines.
- Middleware supports heterogeneity while offering a single system view.
- It provides communication methods for components while hiding differences in operating systems and hardware from applications.
- Differences between computers and communication methods are hidden from users.
- This includes heterogeneous computers and networks, making them easy to expand or scale.
- Continuously available, even if some parts are temporarily out of order.
Goals of Distributed Systems
- Easily connect users/resources.
- Exhibit transparency.
- Support openness.
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Be scalable:
- In size.
- Geographically.
- Administratively.
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Transparency:
- A distributed system is transparent if it presents itself to users as a single system.
- Hides that processes and resources are distributed across multiple computers.
- Types include:
- Access transparency: hides differences in data representation and resource access.
- Location transparency: hides the physical location of a resource.
- Migration transparency: hides if a resource moves.
- Relocation transparency: hides if a resource moves while in use.
- Replication transparency: hides if multiple copies of a resource exist.
- Concurrency transparency: hides that a resource may be shared by multiple users.
- Failure transparency: hides the failure and recovery of a resource.
- Persistence transparency: hides whether a resource is in memory or on disk.
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Openness:
- Offers services according to standard rules with clear syntax protocols of computer networks.
- Includes interoperability (different systems can work together), portability (applications work on different systems), and extensibility (easy to add or modify components).
Scaling Techniques
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Hiding communication latencies:
- Asynchronous communication avoids waiting for responses.
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Distribution:
- Partitions data and computations across multiple machines in the system.
- Includes decentralized naming services (e.g., DNS) and decentralized information systems (e.g., WWW).
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Replication:
- Makes copies of data available at different machines.
- Increases availability, balances load, and hides communication latency.
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Caching:
- Allows client processes to access local copies of data.
- Similar to replication but the decision for caching is made by the client.
- Caching happens on demand while replication is often planned in advance.
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Scalability Problems:
- Size (number of users/processes), geographical (distance between nodes), administrative (number of domains).
- Performance must not degrade with growth.
- Avoid centralized solutions within the system as they can become bottlenecks.
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Consistency Problems:
- Modifying one copy affects others.
- Inconsistency tolerance depends on resource usage.
- Weak consistency (e.g., web caches).
- Strong consistency (e.g., stock exchange).
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Description
Explore the fundamentals of distributed operating systems, focusing on their characteristics and goals. Understand how these systems provide transparency and scalability while connecting users and resources efficiently. This quiz emphasizes the middleware layer that supports heterogeneous environments.
