（254）Which three statements correctly describe the features of the I/O calibration process? (Choose three.)  

A. Only one I/O calibration process can run at a time.

B. It automates the resource allocation for the Automated Maintenance Tasks.

C. It improves the performance of the performance-critical sessions while running.

D. It can be used to estimate the maximum number of I/Os and maximum latency time for the system.

E. The latency time is computed only when the TIMED_STATISTICS initialization parameter is set to TRUE.

答案：（A、D、E）