L05a,b - Distributed Systems

A distributed system is a collection of independent nodes connected via a network that interact through message passing over that network.

The main difference is that distributed systems consist of autonomous nodes connected over a wide network, while parallel systems have tightly integrated nodes within a single physical unit.

Leslie Lamport suggests that Tm must not be negligible compared to the time between events in a single process, indicating significant communication delays in distributed systems.

<p>Distributed systems can operate over various types of networks including Local Area Networks (LAN) and Wide Area Networks (WAN).</p> Signup and view all the answers

<p>The operating system protocol stack is essential as it manages data exchange between nodes, ensuring communication efficiency and reliability.</p> Signup and view all the answers

<p>A distinguishing property of distributed systems is that they have no shared physical memory, with each node possessing its own private memory.</p> Signup and view all the answers

<p>Advancements in shrinking transistor sizes and VLSI technology have blurred the lines between distributed and parallel systems.</p> Signup and view all the answers

<p>Event computation time (Te) refers to the time a single node takes to perform a computation and is significantly less than messaging time (Tm) in distributed systems.</p> Signup and view all the answers

<p>A cluster is considered a distributed system when communication time (Tm) is greater than computation time (Te).</p> Signup and view all the answers

<p>If Tm is much less than Te, it minimizes the time spent in communication, thus maximizing overall system efficiency.</p> Signup and view all the answers

<p>Partial order allows for a sequence of events without strict guidelines, while total order requires a clear, unambiguous sequence of events.</p> Signup and view all the answers

<p>Event 'a' precedes 'b' if the timestamp of 'a' is less than that of 'b' or if the timestamps are equal, a tie-breaking condition is applied.</p> Signup and view all the answers

<p>A tie-breaking rule resolves ambiguities when two timestamps are equal, ensuring a consistent order of events.</p> Signup and view all the answers

<p>It allows processes to timestamp their requests to acquire locks, facilitating coordinated access without shared memory.</p> Signup and view all the answers

<p>It addresses the challenge of implementing mutual exclusion in a distributed system where processes do not share memory.</p> Signup and view all the answers

<p>A node timestamps its request using its local clock and sends a message to all other processes stating its intent to acquire the lock.</p> Signup and view all the answers

<p>The process inserts the request into its local queue, orders it by timestamp, and sends an acknowledgment back to the requester.</p> Signup and view all the answers

<p>A tie is resolved using a tie-breaking rule, such as age-based priority, to determine which request has precedence.</p> Signup and view all the answers

<p>Total order is critical as it provides a deterministic outcome, ensuring a consistent view of events and preventing conflicts.</p> Signup and view all the answers

<p>Logical timestamps indicate the sequence of events and can be used to establish a partial order among them.</p> Signup and view all the answers

<p>If communication time dominates, the benefits of parallelism are reduced as more time is spent on messaging than computation.</p> Signup and view all the answers

<p>Logical clocks help establish a consistent order of events, facilitating coordination among distributed processes.</p> Signup and view all the answers

<p>It has either received acknowledgments from all other processes, or received lock requests from peers with timestamps later than its own request.</p> Signup and view all the answers

<p>The process defers the acknowledgment until it releases the lock, sending the unlock message as a combined acknowledgment.</p> Signup and view all the answers

<p>It reduces the number of messages needed, from 3(N - 1) to 2(N - 1), by combining unlock and acknowledgment messages.</p> Signup and view all the answers

<p>Reliable communication ensures that messages are never lost, thus enabling accurate tracking of lock requests and responses.</p> Signup and view all the answers

<p>Clock drift can cause scheduled transactions to occur earlier or later than intended, leading to transaction failures.</p> Signup and view all the answers

<p>Logical clocks cannot account for physical time discrepancies, which can lead to issues such as incorrect transaction ordering.</p> Signup and view all the answers

<p>It can result in synchronization issues, leading to events occurring in an unintended order when comparing timestamps.</p> Signup and view all the answers

<p>This combination reduces network traffic and improves the responsiveness of the system by cutting down on total message volume.</p> Signup and view all the answers

<p>Researchers can explore advanced algorithms and methodologies to optimize messaging overhead below the current complexity of 2(N - 1).</p> Signup and view all the answers

<p>The debit request was processed before Kishore's deposit due to clock discrepancies, leading to insufficient funds during processing.</p> Signup and view all the answers

<p>One goal is to improve the efficiency and scalability of distributed algorithms, particularly concerning messaging costs.</p> Signup and view all the answers

<p>Clock drift causes a clock to deviate from real time, which affects the timing of scheduled events.</p> Signup and view all the answers

<p>Analyzing messaging complexity helps gauge the efficiency and performance of distributed algorithms, impacting their practical applications.</p> Signup and view all the answers

<p>Operations may execute out of the intended sequence when only logical clocks are used, leading to potential data inconsistency.</p> Signup and view all the answers

<p>A process must insert its request into its local queue and send it to all other processes, ensuring they insert it into their own queues in timestamp order.</p> Signup and view all the answers

<p>A process can assume it has acquired the lock if its request is at the top of its local queue and it has received acknowledgments from all other processes.</p> Signup and view all the answers

<p>Upon receiving an unlock message, a process removes the corresponding request from its local queue.</p> Signup and view all the answers

<p>Lamport's Logical Clocks provide the necessary order for requests and acknowledgments, ensuring consistency across processes.</p> Signup and view all the answers

<p>The total messaging complexity for one lock/unlock operation is $3(N - 1)$, where $N$ is the number of processes.</p> Signup and view all the answers

<p>Messaging complexity can be optimized by improving how acknowledgments are handled among processes.</p> Signup and view all the answers

<p>Maintaining queue ordering based on timestamps ensures that all processes agree on the sequence of requests, preventing conflicts.</p> Signup and view all the answers

<p>Receiving ACK messages confirms that all processes have acknowledged the request, ensuring its legitimacy and order.</p> Signup and view all the answers

<p>If a process receives lock requests with higher timestamps, it can proceed with its own request even if not all ACKs are received.</p> Signup and view all the answers

<p>Message delays can result in some processes receiving requests later than others, causing differences in local queue states.</p> Signup and view all the answers

<p>A fallback condition for lock acquisition is that the process can proceed if it has higher timestamps from received lock requests.</p> Signup and view all the answers

<p>A process releases a lock by removing its request from its local queue and sending unlock messages to all other processes.</p> Signup and view all the answers

<p>The algorithm ensures mutual exclusion by relying on ordered queues and logical clock timestamps for request coordination.</p> Signup and view all the answers

<p>A consistent tie-breaking rule prevents ambiguity in lock acquisition decisions when requests have identical timestamps.</p> Signup and view all the answers

<p>Local decision-making allows each process to manage its own queue and coordinate requests based on received messages.</p> Signup and view all the answers

<p>To synchronize the clocks of computer systems over packet-switched networks.</p> Signup and view all the answers

<p>It ensures local clocks are aligned with a trusted time source to prevent discrepancies.</p> Signup and view all the answers

<p>Logical time orders events causally, while physical time reflects real-world timing of events.</p> Signup and view all the answers

<p>It synchronizes clocks to ensure real-time ordering of events across different processes.</p> Signup and view all the answers

<p>Bound on individual clock drift (PC1) and bound on mutual clock drift (PC2).</p> Signup and view all the answers

<p>It refers to how much a single clock's time deviates from real time.</p> Signup and view all the answers

<p>It is the difference in clock readings between any two processes at the same real time.</p> Signup and view all the answers

<p>They must be negligible compared to inter-process communication time to avoid incorrect event ordering.</p> Signup and view all the answers

<p>PTP provides higher accuracy synchronization than NTP, suitable for time-sensitive systems.</p> Signup and view all the answers

<p>It describes the causal ordering of events, denoted by the symbol '|-&gt;'.</p> Signup and view all the answers

<p>Implementing clock synchronization protocols like NTP or PTP.</p> Signup and view all the answers

<p>They utilize atomic clocks or GPS-based timing to minimize drift in critical systems.</p> Signup and view all the answers

<p>When coordination of events based on real (physical) time is required.</p> Signup and view all the answers

<p>It allows for the implementation of mechanisms to detect and correct time discrepancies.</p> Signup and view all the answers

<p>It can lead to anomalies and inconsistencies in time-dependent operations.</p> Signup and view all the answers

<p>The condition states that mutual clock drift (ϵ) must be less than or equal to the inter-process communication time (μ).</p> Signup and view all the answers

<p>Individual clock drift (k) refers to the maximum rate at which a single clock's time can deviate from real time.</p> Signup and view all the answers

<p>It means that the deviation of a clock over the interval μ should be small enough that it does not affect event ordering.</p> Signup and view all the answers

<p>The receiver's clock at message arrival must read a time greater than or equal to the sender's clock at sending.</p> Signup and view all the answers

<p>In ideal scenarios, clocks should be perfectly synchronized so that Ci(t) = Cj(t) = t for all processes.</p> Signup and view all the answers

<p>This condition ensures that the maximum difference between clocks is accommodated by the time it takes for messages to be sent.</p> Signup and view all the answers

<p>Predictable and bounded communication delays help ensure that clock discrepancies do not interfere with event ordering.</p> Signup and view all the answers

<p>If mutual clock drift exceeds inter-process communication time, it may lead to inaccurate event ordering.</p> Signup and view all the answers

<p>Accurate time synchronization is essential in financial transactions.</p> Signup and view all the answers

<p>The condition is represented as Cj(t + μ) ≥ Ci(t).</p> Signup and view all the answers

<p>Highly accurate clocks ensure minimal drift, which preserves event ordering and prevents anomalies.</p> Signup and view all the answers

<p>If kμ is not negligible, it can lead to inconsistencies in clock readings and event ordering.</p> Signup and view all the answers

<p>Synchronization protocols like NTP and PTP are essential to minimize clock drift, ensuring delays remain predictable.</p> Signup and view all the answers

<p>Controlling ϵ is vital to ensure messages are received in the correct order relative to their sending time.</p> Signup and view all the answers