It could be that RAID is still initializing, you might want to check on the controller to see what % is completed. If it is completed try rebooting the system, though you should not have to we should see if that helps.
What is your DSS build that your system is running now?
In the DSS V6 b5626 this it’s already forbidden to add “volume replication” to a NAS logical volume without deleting the back tasks before and unassigning the snapshot from that logical volume. This should prevent the occurrence of the mentioned failures.
the running version is : 3.11.XE00000001.2522
release date : 2007-01-17
Before we created the Raid volume via 3ware manager, we had delete and remove all existing shares and tasks.
I am not physically present so i cannot test via the console today.
I'll do it tomorrow or monday morning, and if it doesn't work maybe request an intervention from your hotline service to fix it, because it's urgent and touchy (actually our datas are in another NAS, without any backup and security).