It is called Online Capacity Expansion, because you can expand the capacity of your Virtual Disk while the server is online, without affecting data.  It will slow things down a bit - about like a rebuild - so if it is heavily used, I would recommend doing it during off hours. This can be done from the OS if you have OpenManage Server Administrator installed (Storage, PERC, Virtual Disks, Reconfigure from the dropdown menu).
Hi I want to install a new disk in our Poweredge 2950, perc 5/i, to extend an existing virtual disk using RAID 5.  My questions are will it wipe the data that is already being used on this virtual disk and can it be done whilst the server is in use?  Thanks
Will reconfigure virtual disk on Poweredge 2950 format data