We did this procedure on a DELL R730XD SERVER
HIT RECONFIGURE.
FYI WE HAD DATA ON THE F DRIVE IN THIS CASE THAT WAS THE RAID 6
THEN Execute
Then a wizard will come up
Lets say you will add 3 new drives to the raid 6 to expand?
Then select RAID6
Then Continue
Wil get warning
Then this will show
Then press finish
Then this will happen
FYI WE HAD DATA ON THE F DRIVE IN THIS CASE THAT WAS THE RAID 6
WHILE RECONSTRUCTING THE DATA WAS NOT DELETED AND IT IS STILL THE SAME SIZE.
ONCE IT COMPLETED ALL DATA WAS STILL THERE AND PARTITION DID NOT CHANGE IN SIZE, HOWEVER STORAGE DISK SIZE DID AS YOU CAN SEE.
So you can easily expand the partition if needed.