i initially used teracopy because of its file verification via md5 sum. but that seems to take about as long as the data transfer, so its been chugging away for about 5 days now, and that is not a process i want to repeat once a month.
I was initially planning on doing a robocopy /mir type of command, and i figured teracopy had something similar but it does not. Robocopy doesnt verify that the source data is identical to its copy target, which sort of sucks. Due to stuff like files being replaced with identically named (but for example, fixed video) files or files having their metadata updated, i figured robocopy was not the right option unless it is able to copy when "last modified" attribute is set.
im also unsure if i want to be leaving all those external disks plugged in 24/7 or if i just want to power them on right before the monthly backup task runs. im very iffy about seagate drive reliability.