The following description might help you understand the test logic being used in the optical logo test to validate the drive write speed.

The test queries the device and gets the supported write speeds for the test media. Then it will try to validate the write scenario for all the reported write speeds. The test expects the calculated write speeds for each write scenario is close to the write speed set to the drive. The test allows 10% tolerance for the measured write speed. The test validates the write speed as below:

The test writes data to the media and monitors the amount of data being written. It excludes the timing for the initial 10% written data the final 10% written data. It measures the timing only for the in between 80% data and calculates the speed for that data and adds 10% tolerance to that value. So, if ‘x’ is the calculated the speed for the middle 80% data then the final calculated speed is 1.1x. The test expects this value to be greater than or equal to the speed set to the drive before beginning the write.

 

                | ß Initial 10% excluded à | ß Write speed measurement (80%) à | ß Final 10% excluded à |

                                                                                                 (x)

 

The test excludes the initial 10% of data written timing to allow the drive to prepare for writing. The final 10% data timing is excluded to allow the drive to do the proper cleanup for the data written to the media.