The best way to replace is the drive is to replace all the drives at the same time and create a new disk array and logcial drive to increase the size of the volume. When you replace the old drive and start the rebuilding process, the disk drives of different capacities are used, there will also be unused capacity on the larger drive. The RAID Volume’s data capacity equals the smaller disk drive present in the Array.
If you want to access the data from your old drive then, you have to back all the information and then repalce all the drives at the same time with the bigger size drive and create a disk array and logical drive. Once the synchronization is completed, restore the data.
Kindly go to the link below to download the compatibility list for Pegasus2 R6.