The numbers of the chosen physical drives should support the current pool's RAID Level ; The same RAID level should be used for pool expansion.
1].Click the lock to Unlock first after lunch the Promise Utility Pro
2].Click the Controls tab
3].Put the password of the login user
4]. Go to Pools tab and select your pool and then click Expand function
5].Select physical drives you would like to expand. For this case, original pool is with RAID5 level so you at least select 3 disks to expand the pool.
6].Check these drives for the pool at Dashboard tab when pool-expand is done.
7]. Go to Pools tab and select your pool and then click Add Volume function
8].A new Pegasus Volume (VolumeName2) will be mounted after formatting it.