Lesson 7c: Distributed File Systems

The two main goals are metadata management and file caching.

Cooperative caching allows file data to be served from a peer node's memory, minimizing direct disk access.

It is essential because knowledge of file systems aids in understanding how DFS manages files and metadata across distributed nodes.

<p>NFS uses a centralized server model, while DFS distributes files and metadata across multiple nodes to improve scalability.</p> Signup and view all the answers

<p>DFS provides greater I/O bandwidth and distributed metadata management.</p> Signup and view all the answers

<p>DFS can operate as a serverless structure, allowing nodes to function interchangeably as clients or servers.</p> Signup and view all the answers

<p>Careful design maximizes caching, balances load, and efficiently leverages peer memory.</p> Signup and view all the answers

<p>Cooperative caching allows nodes to retrieve data from each other's memory rather than relying on slow disk storage.</p> Signup and view all the answers

<p>The primary limitation is the scalability bottleneck, where a single server must handle all client requests, leading to performance degradation as user demand increases.</p> Signup and view all the answers

<p>Server caching improves performance by storing frequently accessed files in memory, allowing quicker response times by serving files from the cache instead of accessing the disk.</p> Signup and view all the answers

<p>The goal of implementing a DFS is to address scalability limitations of NFS by distributing files and metadata across multiple servers to enhance throughput and reduce bottlenecks.</p> Signup and view all the answers

<p>Cooperative Caching in DFS allows clients to retrieve file data from other clients that have accessed the same file, reducing load on servers and improving data access times.</p> Signup and view all the answers

<p>Distributed metadata management divides metadata responsibilities across multiple servers, reducing the load on any single server and enhancing overall system performance.</p> Signup and view all the answers

<p>A serverless file system allows all nodes to act as both clients and servers, eliminating the traditional client-server hierarchy and increasing system resilience and scalability.</p> Signup and view all the answers

<p>I/O bandwidth in a DFS is enhanced by leveraging the cumulative bandwidth of all servers in the network, allowing for improved data throughput across multiple nodes.</p> Signup and view all the answers

<p>DFS expands caching capacity by utilizing the collective memory of all servers and clients, providing a larger memory footprint for file caching.</p> Signup and view all the answers

<p>RAID increases I/O bandwidth and provides failure protection through error correction codes stored on additional disks.</p> Signup and view all the answers

<p>RAID combines multiple disks to allow parallel data access, improving I/O bandwidth for file systems.</p> Signup and view all the answers

<p>The trade-off includes the need for multiple disks to achieve greater performance and data redundancy.</p> Signup and view all the answers

<p>The foundational concept of RAID is using multiple disks to increase I/O bandwidth, which is crucial for enhancing performance in file systems.</p> Signup and view all the answers

<p>RAID stands for Redundant Array of Inexpensive Disks, and its primary purpose is to increase I/O bandwidth and provide data redundancy.</p> Signup and view all the answers

<p>RAID improves read and write speeds by striping files across multiple disks, allowing simultaneous access.</p> Signup and view all the answers

<p>Error-correcting codes (ECC) in RAID detect and correct errors that may occur during disk reads, enhancing data reliability.</p> Signup and view all the answers

<p>The small write problem occurs when small files require access to all disks, leading to inefficiency and increased access time.</p> Signup and view all the answers

<p>When a disk error occurs, the error-correcting code stored on an additional disk is used to reconstruct the missing or damaged data.</p> Signup and view all the answers

<p>The drawbacks of RAID technology include increased hardware costs due to multiple disks and the inefficiency posed by the small write problem.</p> Signup and view all the answers

<p>When a file is written in RAID, it is divided into parts, with each part being stored on a separate disk along with a checksum on an additional disk.</p> Signup and view all the answers

<p>File striping contributes to increased I/O bandwidth by enabling parallel access to different parts of a file stored on separate disks.</p> Signup and view all the answers

<p>LFS aggregates changes into log segments and writes them to disk sequentially, rather than rewriting entire files.</p> Signup and view all the answers

<p>Changes are buffered in memory as contiguous log segments until they reach a certain threshold to be written to disk.</p> Signup and view all the answers

<p>Log cleaning aims to remove outdated log entries and reclaim disk space by consolidating valid entries.</p> Signup and view all the answers

<p>LFS reconstructs a file by combining the relevant log segments from disk into a coherent file extension.</p> Signup and view all the answers

<p>A log hole refers to invalidated log entries that occupy disk space without holding valid data.</p> Signup and view all the answers

<p>LFS uses append-only logs to manage file changes, maintaining log files instead of traditional data files.</p> Signup and view all the answers

<p>Log segments can be striped across multiple disks in RAID, maximizing I/O bandwidth and improving performance.</p> Signup and view all the answers

<p>Initial read latency occurs because the file must be reconstructed from multiple log segments on disk.</p> Signup and view all the answers

<p>Logs serve as the primary storage medium in LFS.</p> Signup and view all the answers

<p>LFS aggregates file changes into larger log segments for sequential writing.</p> Signup and view all the answers

<p>Initial read latency occurs due to the need to reconstruct files from logs.</p> Signup and view all the answers

<p>Log cleaning is necessary to manage disk space and prevent excessive storage of outdated logs.</p> Signup and view all the answers

<p>Journaling file systems maintain both data files and temporary log files, while LFS only uses logs.</p> Signup and view all the answers

<p>RAID enhances LFS by allowing sequential writes across multiple disks, improving disk efficiency.</p> Signup and view all the answers

<p>LFS only stores logs, requiring reconstruction of data, while traditional systems maintain direct access to data files.</p> Signup and view all the answers

<p>It seeks to resolve the inefficiencies associated with handling small write operations.</p> Signup and view all the answers