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

Define state that process must obtain all resources it needs, Before procee...

Before proceeding with its execution, every process must obtain all the resources it needs is called Hold and wait

Explain the procedure for handling the page fault, The procedure for handli...

The procedure for handling the page fault is as follows 1. We check the internal table to verify whether the reference was valid or invalid. 2. If the reference was invalid,

How virtual memory is implemented, How Virtual memory is implemented Vi...

How Virtual memory is implemented Virtual memory can be implemented along with Segmentation and Paging

What happens when you execute a program in unix, When you run a program on ...

When you run a program on your UNIX system, the system prepares a special environment for that program. This environment owns everything needed for the system to execute the progra

Define the client - server communications environment, Define the Client - ...

Define the Client - Server Communications Environment Today's client - server communications environment offers programmers great flexibility for application design. Applicatio

Difference between two tier and three tier architectures, Question: a) ...

Question: a) Illustrate with the help of a diagram, the difference between two tier and three tier architectures. b) Explain in what kind of environment, a peer to peer envi

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

Facility location, What is the essence of facility location in production o...

What is the essence of facility location in production operation management

Explain objectives of the file management system, Problem: a) Define a ...

Problem: a) Define a ‘file' and list the objectives of the file management system. b) List the ways in which programs access files and determine for what file types you woul

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