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

Difference between internal and external fragmentation, Explain the differe...

Explain the difference between internal and external fragmentation. Internal Fragmentation is the area in a region or a page that is not used by the job occupying that region o

Define unixware, Define UnixWare UnixWare manages resources at the proc...

Define UnixWare UnixWare manages resources at the process level. Each resource allocated to the application is actually allocated to the process representing the application. C

How can application use memory via the win32 api, Q. Explain some of the wa...

Q. Explain some of the ways an application can use memory via the Win32 API. Answer: (1) Virtual memory offers several functions that allow an application to reserve and rele

How many disk operations are needed to fetch the i-node, How many disk oper...

How many disk operations are needed to fetch the i-node for the file /usr/ast/courses/os/handout.t? Assume that the i-node for the root directory is in memory, but nothing else alo

What is an acyclic graph, What is an acyclic graph? A tree that has bee...

What is an acyclic graph? A tree that has been corrupted by links to other branches, but does not have any cyclic paths in it.

Dynamic scheduling, Dynamic scheduling : The number of thread in a program...

Dynamic scheduling : The number of thread in a program may be changed during the course of operation. Dynamic priority scheduling is a kind of scheduling algorithm in which the pr

How many disks can be used effectively by one fast wide bus, Q. More than ...

Q. More than one disk drive is able to be attached to a SCSI bus. Especially a fast wide SCSI-II bus can be connected to at most 15 disk drives. Remember that this bus has a bandw

Processes and programs, Processes and Programs Process is a dynamic...

Processes and Programs Process is a dynamic entity which is a program in execution. A process is a sequence of information executions. Process exists in a limited span of t

How are file sharing and protection implemented, How are file sharing and p...

How are file sharing and protection implemented? To execute file sharing and protection the system have to maintain more file and directory attributes than are needed on a sing

Define cpu scheduling, Define CPU scheduling. CPU scheduling is the met...

Define CPU scheduling. CPU scheduling is the method of switching the CPU among several processes. CPU scheduling is the basis of multiprogrammed operating systems. By switching

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