Distributed File Systems: Caching Mechanisms Review Quiz
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Questions and Answers

What is the primary focus of the Distributed File System (DFS) lesson?

  • Peer-to-peer communication
  • Caching mechanisms (correct)
  • State coordination among servers
  • Client-server architecture
  • In a Distributed File System, which nodes own and manage the state?

  • Peer nodes
  • Server nodes (correct)
  • Client nodes
  • Both client and server nodes
  • What is the characteristic of a Peer Distributed Application?

  • All nodes are peers and share the state (correct)
  • Servers manage the state and clients access it
  • Clients manage the state and servers access it
  • There is no state sharing among nodes
  • What is the overall application state in a Peer Distributed Application?

    <p>The union of all local states (B)</p> Signup and view all the answers

    What is the relationship between nodes in a Peer Distributed Application?

    <p>Peer-to-peer relationship (B)</p> Signup and view all the answers

    What is a characteristic of state in a Peer Distributed Application?

    <p>Some state is locally stored on a particular node (D)</p> Signup and view all the answers

    What is the issue with using variables in a distributed shared memory (DSM) system?

    <p>Variables are still too small and occur too frequently (A)</p> Signup and view all the answers

    What is a more suitable granularity for a DSM system integrated at the operating system level?

    <p>Page-based (D)</p> Signup and view all the answers

    What is the advantage of using page-based granularity in a DSM system?

    <p>It amortizes the cost of remote access across larger granularities (B)</p> Signup and view all the answers

    What is a disadvantage of the language level solution for DSM?

    <p>It is not generalizable outside of programming languages with DSM support (B)</p> Signup and view all the answers

    What is the issue with increasing the granularity of sharing in a DSM system?

    <p>It may lead to false sharing (D)</p> Signup and view all the answers

    What is an example of false sharing in a DSM system?

    <p>Two processes accessing different variables on the same page (A)</p> Signup and view all the answers

    What is the main role of the DSM layer in a single reader/single writer application?

    <p>To provide the application with the ability to access additional, remote memory (A)</p> Signup and view all the answers

    What is the performance metric to analyze in a DSM solution?

    <p>Access latency (B)</p> Signup and view all the answers

    What is a way to maximize the proportion of local memory accesses in a DSM system?

    <p>Through migration (B)</p> Signup and view all the answers

    What is the limitation of the migration solution in a DSM system?

    <p>It incurs overheads (B)</p> Signup and view all the answers

    What is the primary reason for creating page replicas in datacenter environments?

    <p>To triplicate shared state (C)</p> Signup and view all the answers

    What is the role of the manager node in a DSM system?

    <p>To maintain metadata for a particular page (A)</p> Signup and view all the answers

    What is the purpose of the global map in a DSM system?

    <p>To capture the page ID and return a manager ID (C)</p> Signup and view all the answers

    Why does the DSM layer need to intercept every access to the shared state?

    <p>All of the above (D)</p> Signup and view all the answers

    What is the role of the MMU in a DSM system?

    <p>To generate a trap when a valid mapping is not found (A)</p> Signup and view all the answers

    What is the benefit of using a global mapping table in a DSM system?

    <p>It allows for manager node flexibility (B)</p> Signup and view all the answers

    Why is it important to maintain metadata for each page in a DSM system?

    <p>To perform specific access to that page (D)</p> Signup and view all the answers

    What is the advantage of using an object-based DSM system?

    <p>It can be implemented at the level of the programming language runtime (C)</p> Signup and view all the answers

    What is the purpose of the DSM layer in a DSM system?

    <p>To intercept every access to the shared state (A)</p> Signup and view all the answers

    What guarantee do causal consistency models provide in terms of update ordering?

    <p>Correct ordering for causally related updates (A)</p> Signup and view all the answers

    In the weak consistency models, what purpose does a synchronization point serve?

    <p>Ensuring visibility of previous updates at other processors (B)</p> Signup and view all the answers

    What does a synchronization operation performed by P1 after writing to m1 guarantee according to the weak consistency model?

    <p>Visibility of previous updates (C)</p> Signup and view all the answers

    How does the weak consistency model handle synchronization between processors regarding visibility of updates?

    <p>By requiring explicit synchronization calls from relevant processors (A)</p> Signup and view all the answers

    What is the primary purpose of a sync operation in weak consistency models?

    <p>Ensuring the visibility of past updates to all processors (B)</p> Signup and view all the answers

    What is the consequence of not explicitly synchronizing with the rest of the system in weak consistency models?

    <p>Updates may not be immediately visible (C)</p> Signup and view all the answers

    In weak consistency models, when does P2 see all previous updates made to any memory location in the system?

    <p>After a synchronization operation on P2 (D)</p> Signup and view all the answers

    What controls the overheads imposed by the DSM layer in fine-grained synchronization operations?

    <p>Different synchronization operations for different granularities (A)</p> Signup and view all the answers

    What is the purpose of an entry/acquire point in a system providing finer-grained synchronization operations?

    <p>To make all updates visible to a particular process (A)</p> Signup and view all the answers

    How does separating synchronization types into entry/acquire and exit/release points benefit the system?

    <p>Limits data movement and coherence operations (C)</p> Signup and view all the answers

    Why does the solution of permitting multiple copies of the same data page require consistency management?

    <p>To ensure data is propagated across nodes for up-to-date reads (A)</p> Signup and view all the answers

    What is the purpose of consistency management in DSM systems?

    <p>To maintain consistency similar to SMP systems (A)</p> Signup and view all the answers

    What is the strategy called when one processor’s cached value of a variable is invalidated when another processor updates that variable?

    <p>Write-invalidate (D)</p> Signup and view all the answers

    What is the drawback of supporting the write-invalidate strategy in a DSM system?

    <p>The overhead is too high once network costs are considered (C)</p> Signup and view all the answers

    What is the purpose of the home node in a DSM system?

    <p>To drive all of the coherence operations related to a page (D)</p> Signup and view all the answers

    What is the role of the owner node in a DSM system?

    <p>To currently own the page and control all of the state modifications (C)</p> Signup and view all the answers

    What is the purpose of separating the distinction of home node from an owner node in a DSM system?

    <p>To allow for efficient handling of repeated access to a page by a node that is not its home node (A)</p> Signup and view all the answers

    What is the purpose of caching in a DSM system?

    <p>To achieve low latency and performant system (B)</p> Signup and view all the answers

    What is the global shared memory composed of in a DSM system?

    <p>The memory pages that each node contributes towards the DSM system (C)</p> Signup and view all the answers

    What is the purpose of the DSM layer in a DSM system?

    <p>To incorporate caching to achieve low latency (B)</p> Signup and view all the answers

    What is the primary purpose of a consistency model in a distributed system?

    <p>To provide a guarantee that state changes will behave in a certain way (C)</p> Signup and view all the answers

    What is the main constraint of the interleaving in sequential consistency?

    <p>Updates from the same process will not be arbitrarily interleaved (A)</p> Signup and view all the answers

    What is the main difference between strict consistency and sequential consistency?

    <p>Strict consistency guarantees immediate visibility, while sequential consistency does not (D)</p> Signup and view all the answers

    Why is strict consistency impossible to achieve in practice?

    <p>It is impossible to guarantee ordering of accesses from different cores without locking and synchronization (D)</p> Signup and view all the answers

    What is the main advantage of sequential consistency over strict consistency?

    <p>It is more suitable for distributed systems (D)</p> Signup and view all the answers

    What is the main goal of causal consistency?

    <p>To allow processes to see different updates based on their dependencies (D)</p> Signup and view all the answers

    What is the main limitation of strict consistency?

    <p>It is impossible to guarantee instantaneous updates (A)</p> Signup and view all the answers

    What is the relationship between the consistency model and the software layers in a system?

    <p>The software layers must follow certain rules to achieve the consistency model (B)</p> Signup and view all the answers

    Why is it important to ensure that the way operations access memory is representative of how the operations were issued?

    <p>To ensure that memory behaves correctly (B)</p> Signup and view all the answers

    What is the main advantage of consistency models in distributed systems?

    <p>They provide a guarantee that state changes will behave in a certain way (C)</p> Signup and view all the answers

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