In the following questions, one or more participants in a distributed commit hav
ID: 3873238 • Letter: I
Question
In the following questions, one or more participants in a distributed commit have undergone failure. Upon recovery they are able to retrieve the shown information from the other members of the other participants in the commit. Given this information decide what action the group should take - either commit, abort, or wait for further response?
4.
Coordinator: Commit
Cohort A: Promise
Cohort B: Promise
Cohort C: Commit
Cohort D: Promise
5.
Coordinator: Abort
Cohort A: No Response
Cohort B: No Response
Cohort C: No Response
Cohort D: No Response
6.
Coordinator: No Response
Cohort A: Promise
Cohort B: Promise
Cohort C: Promise
Cohort D: Commit
7.
Coordinator: No Response
Cohort A: Promise
Cohort B: Promise
Cohort C: Promise
Cohort D: Promise
8.
Coordinator: No Response
Cohort A: Abort
Cohort B: Abort
Cohort C: Promise
Cohort D: Promise
Explanation / Answer
Please follow the below answers and specify detail and clear information.
Though here is a possible exaplanation given below.
4.
Coordinator: Commit
Cohort A: Promise
Cohort B: Promise
Cohort C: Commit
Cohort D: Promise
Answer:
Cohort A , B , D are in first phase to ready to commit and C is already committed locally and sends ACK to Coordinator.
After that, in phase2 if all four A,B,C,D are ready to commit then Coordinator will declared a global commit.
5.
Coordinator: Abort
Cohort A: No Response
Cohort B: No Response
Cohort C: No Response
Cohort D: No Response
Answer:
In first phase Cohort A , B , C, D either minimum one of them are not prepared or all four are not voted for commit or say NO to proceed locally, then all of those four are either going to be aborted or any one or two are aborted or time out.
After that, in second phase Coordinator will declared a global abort .
6.
Coordinator: No Response
Cohort A: Promise
Cohort B: Promise
Cohort C: Promise
Cohort D: Commit
Answer :
Cohort A,B,C are in prepared phase or first phase and ready to keep promise to commit locally where D is already vote for commit and give an ACK to Coordinator.So ethically coordinator needs to declare global commit.
But here, as coordinator does not respond to slaves, so it must be globally aborted.
7.
Coordinator: No Response
Cohort A: Promise
Cohort B: Promise
Cohort C: Promise
Cohort D: Promise
Answer:
All four are in first phase and give an ACK to coordinator to ready for committing locally. So in second phase coordinator ethically needs to respond global commit.
But here, as coordinator does not respond to slaves, so it must be globally aborted.
8.
Coordinator: No Response
Cohort A: Abort
Cohort B: Abort
Cohort C: Promise
Cohort D: Promise
Answer:
Here, cohort A,B are not to ready to commit locally, so give an ACK to coordinator to abort, where as C,D are prepared to commit locally and as minimum one of them wants to abort, then coordinator needs to declare globally aborted.
But here as coordinator does not respond to slaves , so it is obvious that the whole system must be globally aborted.
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