What inference does recovery in distributed systems, Operating System

Assignment Help:

Q. Consider a distributed system with two sites A and B. Consider whether site A can distinguish among the following:

a. B goes down.

b. The link between A and B goes down.

c. B is much overloaded and its response time is 100 times longer than normal.

What inference does your answer have for recovery in distributed systems?

Answer: One technique would be for B to at regular intervals send an I-am-up message to a indicating it is still alive. If A doesn't receive an I-am-up message it can assume either B-or the network link-is down.

Note that an I-am-up message doesn't permit A to distinguish between each type of failure. One technique that permits A better to determine if the network is down is to send an Are-you-up message to B using an exchange route. If it obtains a reply it can determine that indeed the network link is down and that B is up.

If we presume that A knows B is up and is reachable (via the I-am-up mechanism) in addition to that A has some value N that indicates a normal response time A could monitor the response time from B and compare values to N permitting A to determine if B is overloaded or not.

The inferences of both of these techniques are that A could choose another host-say C-in the system if B is either down or unreachable and or overloaded.


Related Discussions:- What inference does recovery in distributed systems

What is segmentation?, What is segmentation? In a segmented memory mana...

What is segmentation? In a segmented memory management scheme a programmer views a program to be collection of program components called as segments. Every segment is a logical

Explain the resource ownership and control, Explain the Resource Ownership ...

Explain the Resource Ownership and Control Operating systems are required to handle many different types of resources. CPU , memory, and I/O devices  are some of the varied sys

Define approaches that require knowledge of the system state, Define approa...

Define approaches that require knowledge of the system state?  Answer: Deadlock detection, Deadlock prevention, Deadlock Avoidance.

Write a short note about the different states of a process, Write a short n...

Write a short note about the different STATES of a process. As a process implement it changes state. The state of a process is described in part by the current activity of that

Naming scheme for servers in an enterprise, Problem: Within a corporate...

Problem: Within a corporate environment, there are usually many servers located across various departments. Naming of servers is often a tedious task. In many circumstances, w

Reference counting, The idea of reference counting is to maintain, for ever...

The idea of reference counting is to maintain, for every object, the total number of references to that object, i.e. the number of "incoming" pointers. Whenever the number of refer

What is process control block, What is process control block? Every pro...

What is process control block? Every process is represented in the OS by a process control block. It has many pieces of information associated with an exact process.

Explain single level directory structure, Single level directory: This ...

Single level directory: This is the easiest directory structure. All the files are controlled in the same directory, which is simple to support and understand. Few of the li

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd