is it possibnle that the high amount of mirrored data is becasue the VMs are thin provisioned?
Is not possible.
Mirrorview works on block replication.
If you have high I/O write on a thin provisioned disk, then you will have the same I/O write on a thick disk.
Check your VM to see were are all those write operations.
Andre
Andrew | http://about.me/amauro | http://vinfrastructure.it/ | @Andrea_Mauro