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Oracle 1z0-066: Which redo transport mode, and which protection mode should configure?

By: Author Alex Lim

Posted on  - Last updated:

Categories Exam

Question

You must configure an Oracle Data Guard environment consisting of:

  1. A primary database
  2. A Physical Standby Database
  3. A Snapshot Standby Database

You must meet these requirements:

  1. Primary database availability should not be compromised by the availability of the standby databases.
  2. Under normal operations, transactions executed on the primary database should not commit before redo is written to disk on the primary database and on at least one standby database.

Which redo transport mode, and which protection mode should you configure to meet these requirements?

A. SYNC AFFIRM and Maximum Protection
B. SYNC NOAFFIRM and Maximum Protection
C. SYNC AFFIRM and Maximum Availability
D. SYNC NOAFFIRM and Maximum Availability
E. ASYNC and Maximum Performance

Answer

C. SYNC AFFIRM and Maximum Availability

Explanation

The correct answer is C. SYNC AFFIRM and Maximum Availability.

Here is my explanation:

  • The requirement of not compromising the primary database availability by the standby databases rules out Maximum Protection mode, which would shut down the primary database if a fault prevents it from writing its redo stream to at least one synchronized standby database. Therefore, options A and B are incorrect.
  • The requirement of not committing transactions on the primary database until redo is written to disk on the primary database and on at least one standby database rules out ASYNC redo transport mode, which writes the redo data to the local redo log asynchronously with respect to the commitment of the transactions. Therefore, option E is incorrect.
  • The only remaining option is SYNC AFFIRM and Maximum Availability mode, which provides the highest level of data protection that is possible without affecting the availability of the primary database. In this mode, transactions do not commit until all redo data needed to recover those transactions has been written to the online redo log and to at least one synchronized standby database. If a fault prevents the primary database from writing its redo stream to a synchronized standby database, it will operate in RESYNCHRONIZATION until the fault is corrected and all log gaps have been resolved. This mode ensures that no data loss will occur if the primary database fails, but only if a second fault does not prevent a complete set of redo data from being sent from the primary database to at least one standby database.

Reference

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