Copying data to a Mirrored device

[barrysharp]

I schedule SD! to copy two sub folders from a LaCie 6TB RAID-0 Thunderbolt-1 device to another LaCie 4TB RAID-1 (Mirrored) Thunderbolt-1 device.

The amount of data in the LaCie 6TB RAID-0 Thunderbolt-1 device's sub folders is around 960 GB.

If I manually run the schedule back to back the 2nd run is finding tons of new data to copy. I add no new data or modify any data on the source device.

At this time I'm running another manual copy and so far it reports

227,217 of 369,604 files evaluated, 820 files copied....
972.17 GB evaluated, 822.11 MB already up to date, 449.53 GB copied.

I'm absolutely confused as to why SD! is continually thinking it must update the mirrored device with so much data each time beyond its first run.

Is the mirrored destination device causing this issue.

FYI...
I used Apple's Disk Utility to mirror the LaCie 4TB RAID-1 (Mirrored) Thunderbolt-1 device under Yosemite. I'm running SD! under El Capitan.

I'd like some explanation for the above situation. Thanks.

[dnanian]

My guess is that you have some date values that aren't replicateable on the destination. Did any of the content come from a Windows system or server?

[barrysharp]

Whoops.... my mistake here. The scheduled copy was somehow set to erase before copying. I redid the schedule to use Smart update and all is now working as it should. Sorry for posting this bogus error. My bad.... sorry.

[dnanian]

Ah, sorry. I hadn't considered that you might not be using Smart Update! :)