6. Sistem Terdistribusi, Sinkronisai (Waktu)

Summary

This lecture delves into the fundamentals of distributed systems, with a focus on synchronization. The instructor explains key concepts such as Universal Time Coordinated (UTC), tracking time, and the importance of synchronization in distributed file systems and vehicle tracking systems. The session covers various synchronization methods, including Christian's Algorithm and Network Time Protocol (NTP), and discusses practical issues like clock drift and the coordination of processes accessing shared resources. The lecture emphasizes the role of time synchronization in ensuring smooth operation in distributed environments, with examples and algorithms that aid in addressing time-related challenges.

Takeaways

• 😀 Distributed systems require synchronization between entities to prevent issues like data corruption when accessing shared resources.
• 😀 Time synchronization ensures that multiple processes can work together without conflicts, such as in file writing in distributed file systems.
• 😀 Real-world examples, like vehicle tracking systems and distributed file systems, highlight the importance of accurate time synchronization.
• 😀 UTC (Coordinated Universal Time) is the standard time used to synchronize all computers in a distributed system.
• 😀 The concept of clock drift (Clock Q) refers to the deviation between a computer's clock and the actual time, influenced by hardware imperfections and temperature variations.
• 😀 Christian's Algorithm (1989) is a widely used method for synchronizing networked computers through a time server, estimating network delays to adjust time.
• 😀 Synchronizing clocks between different entities ensures correct order of events in distributed systems, preventing inconsistencies.
• 😀 Mutual exclusion is essential for coordinating processes that access shared resources, ensuring no conflicts or data corruption occurs.
• 😀 Algorithms like Christian's Algorithm and NTP (Network Time Protocol) help maintain time accuracy across all computers in a distributed system.
• 😀 Time synchronization plays a crucial role in various applications like ATM networks, banking systems, and e-commerce, where accurate time management is critical.

Q & A

What is the main topic discussed in the lecture?

The main topic of the lecture is synchronization in distributed systems, focusing on concepts like UTC (Universal Time Coordinated), time synchronization algorithms, and the importance of clock synchronization in ensuring the correct operation of distributed systems.

What is UTC, and why is it important in distributed systems?

UTC (Universal Time Coordinated) is the global standard for timekeeping. It is important in distributed systems because it serves as the reference time to synchronize clocks across multiple computers or devices, ensuring consistent time across the entire network.

What is clock drift, and how does it affect distributed systems?

Clock drift refers to the discrepancy between the time kept by different computers' clocks, caused by factors like hardware imperfections or temperature fluctuations. It affects distributed systems by creating time discrepancies between devices, which can lead to errors in coordination and synchronization.

What is Christian's Algorithm, and how does it help synchronize time?

Christian's Algorithm, introduced in 1989, is a method for synchronizing clocks in a distributed system. It involves a client sending a request to a time server, which then responds with the current time. The client then compensates for network delays to adjust its clock, ensuring synchronization with the server.

How does the concept of mutual exclusion relate to synchronization in distributed systems?

Mutual exclusion is a concept that ensures only one process can access a shared resource at a time. In distributed systems, mutual exclusion is important to prevent conflicts, such as when multiple processes try to modify the same file simultaneously, which can lead to data corruption.

What are some practical examples of synchronization in distributed systems mentioned in the lecture?

The lecture mentions two examples: vehicle tracking in a city surveillance system, where cameras synchronize their time to track and report vehicle positions, and distributed file systems, where synchronization ensures that multiple clients don't simultaneously modify the same file, avoiding data corruption.

Why is synchronization important in distributed file systems?

Synchronization is critical in distributed file systems to prevent data corruption. If multiple clients access and modify the same file without proper synchronization, the data can become inconsistent, leading to errors and loss of information.

What assumption does Christian's Algorithm make about network delays?

Christian's Algorithm assumes that the round-trip network delay is the same for both the request and response between the client and the time server, allowing the client to estimate the network delay and adjust its clock accordingly.

What is the role of hardware timers in maintaining time on a computer?

Hardware timers generate interrupts at regular intervals to maintain time on a computer. However, due to imperfections in hardware and temperature fluctuations, these timers can experience drift, causing the computer's clock to run either too fast or too slow compared to actual time.

What challenges arise due to clock drift, and how is it addressed in distributed systems?

Clock drift can lead to time discrepancies between computers in a distributed system, which may cause errors in time-sensitive operations. It is addressed by using algorithms like Christian's Algorithm and synchronizing clocks to a global standard time, such as UTC, to minimize these discrepancies.