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

Explain the spawnvp function used in the netware, Explain the Spawnvp Funct...

Explain the Spawnvp Function used in the netware Spawnvp(flags, execNmae, argv)   This function executes  similarly to spawnlp( ) except that parameters are passed as a v

Determine what a locality of reference entails, Locality of reference entai...

Locality of reference entails that the page reference being made by a process  Locality of reference entails that the page reference being made by a process is similarly to be

Explain what isam, Explain what ISAM is. Indexed sequential access meth...

Explain what ISAM is. Indexed sequential access method. The file is stored in sorted order. ISAM has a master index file, indicating in what part of another index file the key

Interprocess communication, Now we consider the following questions: how ca...

Now we consider the following questions: how can the parent process communicate with its child? Or how can children processes communicate with other children? The exact answer depe

List three ways of allocating storage, List three ways of allocating storag...

List three ways of allocating storage, and give advantages of each. a. Contiguous allocation. Fastest, if no changes are to be made. Also simplest for random access files. b

Explain structure, Explain Structure The Grammar for programming langua...

Explain Structure The Grammar for programming language is a formal description of Structure

Demand paging, Demand paging gives that pages could only be brought into ...

Demand paging gives that pages could only be brought into memory if the running process acts them. This is usually referred to as lazy evaluation as only those pages operated by

What is the translation lookaside buffer, What is the Translation Lookaside...

What is the Translation Lookaside Buffer (TLB) In a cached system, the base addresses of the last few referenced pages is maintained in registers known as the TLB that aids in

Define the tlsfree(tlsindex) function, Define the TlsFree(TLSIndex) Functio...

Define the TlsFree(TLSIndex) Function This function should be called to free a TLSindex allocated by TlsAlloc. It would be executed when there are no more threads in a process

Explain the advantage of assembly language, Explain the Advantage of Assemb...

Explain the Advantage of Assembly Language The advantages of assembly language program is: a)    Reduced errors  b)    Faster translation times  c)    Changes could be ma

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