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63. Examine the values for the following initialization parameters:

FAST_START_MTTR_TARGET = 0

LOG_CHECKPOINT_INTERVAL = 0

Which two will be the implications of these values in your database? (Choose two.)

A.The SGA advisor will be disabled.

B.The MTTR advisor will be enabled. 

C.Automatic checkpoint tuning will be disabled.

D.Checkpoint information will not be written to the alert log file.

Answer: BC  

答案解析：

此題的答案有誤。

 

 

Enabling MTTR Advisor

To enable MTTR Advisor, set the two initialization parameters STATISTICS_LEVEL and FAST_START_MTTR_TARGET.

STATISTICS_LEVEL governs whether all advisors are enabled and is not specific to MTTR Advisor. Ensure that it is set to TYPICAL

 or ALL. Then, whenFAST_START_MTTR_TARGET is set to a nonzero value, the MTTR Advisor is enabled

Automatic Checkpoint Tuning in 10g [ID 265831.1] How to enable: Automatic checkpoint tuning is enabled by default. If it is disabled, by setting the parameter to zero explicitly, you can enable it by unsetting FAST_START_MTTR_TARGET or set it to a nonzero value.  If you set this parameter to zero this feature will be disabled. Note: this is different from defaulting (i.e. not setting) fast_start_mttr_target to 0. 有官方檔案看出， FAST_START_MTTR_TARGET  為0是禁用的，故本題的B是錯誤的，圖中的B的正確的。為C也是正確的。 參考： http://blog.csdn.net/rlhua/article/details/12616383

 MTTR 指導可將FAST_START_MTTR_TARGET值轉換為多個引數，以便在所需時間內（或者在儘量接近此時間的範圍內）啟用例項恢復。請注意，將 FAST_START_MTTR_TARGET引數顯式設定為0會禁用MTTR 指導。 FAST_START_MTTR_TARGET引數的設定值必須支援系統的服務級協議。如果MTTR 目標的值較小，則會因增加了資料檔案寫入次數而增加I/O 開銷（這會影響效能）。但是，如果MTTR 目標設定得過大，則例項在崩潰後需要花費較長的時間才會恢復。
而快速啟動檢查點功能是通過指定所需的非零恢復平均時間（MTTR）值來啟用的，該值將用於設定FAST_START_MTTR_TARGET初始化引數。此引數控制資料庫對單個例項執行崩潰恢復所花費的時間量。啟用快速啟動檢查點功能時，oracle將自動保持檢查點的速度，已便達到請求的MTTR.如果將該值設定為0，將禁用此功能。            

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