The Snap 4500 uses an "invisible N-Way RAID" for the OS in the first 100 MB of each hard drive.
Replacing the drives, one at a time will work, but the data RAID set will still be the original size.
To use the full size of the new drives the original data RAIDset must be deleted and recreated.
Because of this I advise the following method:
Backup the data on the RAID.
Remove the original RAIDset.
Replace 3 drives. (keep the originals untouched, in case something goes wrong)
Go have lunch while the OS RAIDset syncs the N-Way raid.
Once the OS RAIDset is repaired, replace the 4th drive.
Create a new RAIDset using the full drive size.
