@mk so, it seems scrub *does* detect the correct number of bytes but after a certain number qualifies that as "(~2TB)" - forcing it to "3000G" didn't work out because then near the end it craps out with "write /dev/sdc: No space left on device". :( OK - first pass of first scrub completed - I'll try again, without '-s 3000G' and specifying a different method...