Transfer Rates during Erase Surface Test

How are the transfer rates during the Erase surface test calculated? A recent test I ran showed a pretty consistent 220 MB/s transfer rate, which I know the drive is incapable of supporting. The read test stats start at around 130 MB/s and drop to about 70 MB/s over the course of the test, which is what I would expect.

I just want to be sure that the test environment is set up properly before running the test. I already discovered in Windows 7 that if the drive previously had a volume, you have to delete the volume and reboot Windows or the test will return ridiculous results (claiming a 40 GB/s transfer rate and identifying almost all blocks as bad).

Thanks!

Chasman