The Reconfigure is designed to add space to an existing array on-the-fly and while online, so your data will be safe, however, you should never be without a backup. OMSA can be downloaded from the Support Site. If you need a link, let me know which OS you are running.
I am running out of storage and need to add a hard drive.  I currently have PE 1900, PERC 5i, 3 146 GB SAS drives. I think I have RAID 5 config.   I just purchased from dell a 4th 300GB hard drive ( they dont sell the 146 anymore.)  The salesman said I can just add this to the rack and it will be automatically recognized and configured into the 3 current drives.  Is this correct? Thx
Hard drive addition to Power Edge 1900