Approximate RAID rebuild times
To calculate the rebuild time, multiply one HDD by 3 to get the rebuild hours. For example, a 2TB RAID1 will take 3 hours (1TB drive x 3), and a 10TB RAID1 will take 15 hours (5TB x 3).
For SSDs, the rebuild hours are estimated by taking the size of the entire RAID and dividing by 4. For example, a 4TB SSD RAID1 will take 1 hour to rebuild (4TB divided by 4).