Dell PowerEdge - Add new disk to an existing RAID 5 array

Solution 1:

I found the solution by myself, and here is how to achieve this WITHOUT data loss:

With the disk inserted, go to OMSA (OpenManage) > Storage > PERC > Enclosure/Backplane > Physical Disks, and make sure your disk is showing 'Ready'. If you don't see the disk, you may need to reboot for the disk to be detected in OMSA.

If the new disk's status is 'Foreign', go to OMSA > Storage > PERC > Information/Configuration (link at top of page). Choose 'Foreign/Clear' from the dropdown menu. Then disk should enter a 'Ready' state.

If the new disk's status is 'Ready', go to OMSA (OpenMange) > Storage > PERC > Virtual Disks. Choose 'Reconfigure' from the dropdown menu for your RAID 5, follow the wizard to add the physical disk to the array.

Source: http://en.community.dell.com/support-forums/servers/f/906/t/19378577.aspx