> smart will warn you that the problem is close in many cases...
According to Google, about two thirds of the time, SMART will warn you.
> there's also a chance of common fault in both drives.
Never, ever trust a RAID array made from identical disks. Whenever possible use different manufacturers, different models and different batches. Whatever caused failure of one drive will eventually cause the failure of its twins. If all twins are in the same array, you won't be happy.
According to Google, about two thirds of the time, SMART will warn you.
> there's also a chance of common fault in both drives.
Never, ever trust a RAID array made from identical disks. Whenever possible use different manufacturers, different models and different batches. Whatever caused failure of one drive will eventually cause the failure of its twins. If all twins are in the same array, you won't be happy.