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Section A.34. Chapter 17: Case Scenario Answers

A.34. Chapter 17: Case Scenario Answers

A.34.1. Case Scenario: Planning for High Availability

A: Correct Answer: C
  1. Incorrect: Although transactional replication with the queued updating subscribers option enables changes to be made at both locations and can arbitrate data conflicts, it does not provide the flexibility of merge replication.

  2. Incorrect: Log shipping does not allow changes to be made at both the primary and secondary.

  3. Correct: Merge replication enables changes at both the publisher and subscriber while also allowing advanced conflict resolution that enables the conflicting changes to the order quantity to be averaged, allowing a more accurate reflection of the actual inventory on hand.

  4. Incorrect: Database Mirroring does not allow changes to occur on the mirror database.

A: Correct Answer: A
  1. Correct: Log shipping requires the least amount of effort because it just uses the backups that are already being executed against the database. It also leaves the database inaccessible on the secondary.

  2. Incorrect: Replication would have to be configured in this environment, which would take more effort than just reusing the backups that are already being executed. However, replication does not transfer all the objects within the database by default. Transactional replication would need to be either custom-coded to have the identity property already on columns, or it would require the creation of scripts to reintroduce the identity property (which would require much more effort than log shipping).

  3. Incorrect: Replication would have to be configured in this environment, which would take more effort than just reusing the backups that are already being executed. However, replication does not transfer all the objects within the database by default. Changes could be made at the subscriber and sent back to the publisher, which would violate the business requirements.

  4. Incorrect: Replication would have to be configured in this environment, which would take more effort than just reusing the backups that are already being executed. However, replication does not transfer all the objects within the database by default. Changes could be made at the subscriber and sent back to the publisher, which would violate the business requirements.

A: Correct Answer: D
  1. Incorrect: RAID 5 provides minimal fault tolerance by maintaining a hot spare. If more than one disk were to fail, both databases would be offline.

  2. Incorrect: RAID 0 does not provide any fault tolerance, so it is not an appropriate solution.

  3. Incorrect: RAID 1 provides complete redundancy of each disk, but it does not perform as well as RAID 1 + 0 (stripe of mirrors).

  4. Correct: RAID 1 + 0 (stripe of mirrors) provides maximum redundancy while also achieving the best possible performance.

A: Correct Answer: B
  1. Incorrect: Merge replication allows changes to be made at the subscriber and sent back to the publisher, which would violate the business requirements.

  2. Correct: Transactional replication maintains the replica within the marketing department on a near-real-time basis while also preventing any changes from going back to production.

  3. Incorrect: Snapshot replication does not refresh the data as frequently as transactional replication and would cause inconsistencies in the reports that were being executed while a snapshot was being applied.

  4. Incorrect: The immediate updating subscribers option allows changes to be sent back to the publisher, which violates the business requirements.

A: Correct Answer: A
  1. Correct: The peer-to-peer configuration enables additional read and write capacity while also maintaining a single coherent copy of all data throughout the environment. Future expansion is also possible because the deployment can initially have two databases and then add additional databases as the user load requires. The applications must ensure that writes are partitioned between the databases so that data conflicts do not occur.

  2. Incorrect: The bidirectional configuration does not provide any expandability beyond the initial two publisher/subscribers.

  3. Incorrect: Transactional replication can scale the read capacity but not the write capacity.

  4. Incorrect: Transactional replication with the queued updating subscribers option could enable reads and writes to scale to more than one server. However, it introduces much more latency than a peer-to-peer configuration, so users could see logical inconsistencies with their data because of replication latency.


  

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