[ovirt-users] Increasing an Existing iSCSI Storage Domain

My Question is not so much in how to do this as i have been able to take an existing Storage domain and increase its size with adding another LUN. My Question is how will a failure of one of the LUNs be handled by the engine and how will it effect the VMs running on it. Let me setup an example to better illustrate. Ovirt Node has ISCSI storage domain comprised of 1 Lun from 1 ISCSI based SAN and 2 LUNs from another. So a total of 3 Luns making up the one storage domain. Now there is an issue with the Storage array providing the single lun. What happens? How do you know what VMs are running on each extent? TIA Brian