I have just bought 4 4TB Western Digital Red Plus drives, and am in the process of having Scanner scan them for the 1st time. All have the same firmware version.
3 of them scan at about 1% every 25 seconds (increasing by about 0.13% each time), while the 4th scans at 1% about every 113 seconds (increasing by about 0.02% each time). What might account for this variation?