Pre-emptive swap
My preferred technique is to replace one of the drives in a RAID1 after a year. Then at least I know the two are not from the same batch.
Just never, ever use a hardware RAID controller. They use nasty, proprietary disc formats that are unreadable without the correct RAID card; and have an unfortunate tendency to attempt to rebuild an array by copying the new, pristine drive over the one that used to have all the data on it.
Biting the hand that feeds IT
