philsparks

Hi - sorry if this is a bit of a newbies question. I've had drivepool and scanner for approx 2 months on a WHS2011 machine and it's already saved me from one dead seagate drive. I have two 3TB drives with 2x duplication switched on for the entire drive pool, I have about 2.1TB of data. Normally when I look at the drivepool display it normally shows the bar line for each drive being about 2/3 full with the entire line pale blue, i.e all the data is duplicated. I heard the server chugging away quite a bit this afternoon so had a look at what drivepool was up to. I was suprised to see that both disks had around 25% unduplicated and 75% duplicated. (see screen shot) Also both lines are in total shorter than they had been. There was 1.4tb duplicated then approx. 0.35tb unduplicated on each disk, so adding up to the original 2.1tb, but with 0.7tb only stored once and spread across the two disks. The activity bar at the bottom says "duplicating". As I waited it seemed to continue to duplicate and the pale blue line on each drive slowly grew. I understand that drive pool will do some checking and maintenance, but I'd have thought it would do this on a file-by-file basis - in this case it seems to have put a huge amount of my data at risk. I have scanner running and it is showing all drives healthy. Can anyone explain what the programme might be doing and why it's putting my data at risk? thanks Phil