What sort of system have you? If you had, say, an HP Proliant, they are generally fitted with a SmartArray controller card (Hardware RAID.
When a disk fails the array controller marks the disk as faulty and lights an amber indicator to show which disk has failed. You can then replace the drive "live" without damaging anything, the RAID controller re-constructs the data from the remaining drive(s)while in this state so the system is still useable. The replacement disk will then rebuild automatically without system intervension, shown by a flashing green "Disk" led on the front, then rejoin the RAID.
If you have a software RAID, I've no experience, but I would think you would have to go through a software remove and replace process. You shouldn't need to go through any partitioning and re-installing of software in either instance.