adding new hard disk to ESXI server

hi.

we have to proliant dl 380p g8 server and instaling ESxi on that.

on that server have a 3 hard disk with raid5 . now we want to add some hard to this servers and i want now we must raid the new hards seperatly or in new hp server have a new feature that adding this hard to exsiting  raid?

or create new raid from this new hard disk dos not create any problem to my esxi?

than's.