266.View the Exhibit to examine the parameters set for your database instance. You execute the following command to perform I/O calibration after the declaration of bind variables in the session that are used in the command:
SQL> EXECUTE dbms_resource_manager.calibrate_io( num_physical_disks=>1, -
    max_latency=>50, -
     max_iops=>:max_iops, -
     max_mbps=>:max_mbps, -
     actual_latency=>:actual_latency);

Which statement describes the consequence?
A. The command produces an error.
B. The calibration process runs successfully TaMnd populates all the bind variables.
C. The calibration process runs successfully but the latency time is not computed.
D. The calibration process runs successfully but only the latency time is computed.
Answer: A

Oracle 11g数据库中提供了DBMS_RESOURCE_MANAGER.CALIBRATE_IO PL/SQL过程用于对当前数据库实例的I/O性能进行测试。
DBMS_RESOURCE_MANAGER.CALIBRATE_IO的参数如下：

DBMS_RESOURCE_MANAGER.CALIBRATE_IO (  num_physical_disks		IN  PLS_INTEGER DEFAULT 1,  max_latency			IN  PLS_INTEGER DEFAULT 20,  max_iops			OUT PLS_INTEGER,  max_mbps			OUT PLS_INTEGER,  actual_latency			OUT PLS_INTEGER);

可以使用如下方法进行调用测试：

SET SERVEROUTPUT ON
DECLARE
  lat  INTEGER;
  iops INTEGER;
  mbps INTEGER;
BEGIN
-- DBMS_RESOURCE_MANAGER.CALIBRATE_IO (<DISKS>, <MAX_LATENCY>, iops, mbps, lat);
   DBMS_RESOURCE_MANAGER.CALIBRATE_IO (1, 100, iops, mbps, lat);

  DBMS_OUTPUT.PUT_LINE ('max_iops = ' || iops);
  DBMS_OUTPUT.PUT_LINE ('latency  = ' || lat);
  DBMS_OUTPUT.PUT_LINE ('max_mbps = ' || mbps);
end;
/

其中num_physical_disks参数根据当前系统中的disk个数进行设置，在虚拟环境中，可能要选取不同的数值进行测试比较，以获得最佳测试效果。

ITPub博客

1Z0-053 V13.02 Q266

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