As far as expanding the group, you will need to backup and restore the data so you can rebuild the new raid set. It will not retain your data."
If you have the current BIOS and Drivers, you CAN expand the volume without losing data. However, you cannot expand the logical drive(s) (C:, D:) without a third party utility like Acronis Disk Server Suite or other server aware partition manager."
The above accepted and assisted solutions in a related post seem to conflict.
Can two additional drives be added to an existing raid array (PERC 6/i SCSI - PowerEdge 2950 - 4 slots used, 2 slots free) without losing data or having to backup, restore and rebuild? And, will the Dell OpenManage software perform this task from within windows or is Ctrl-r into controller configuration utility on POST required.