The maximum size of physical disk that the PERC 5 can take is 2TB. To make your RAID 5 larger, you can add disks to it - for example, you can convert your 3-disk RAID 5 to a 4- or 5-disk RAID 5 for additional space.  If you replace the existing disks with larger ones, allowing each to rebuild, you will have a VD (Virtual Disk - array) that is the same size as the original - you cannot expand a RAID array that way on the PERC's.  If you replace each (and every) disk with a larger one, the only thing you will be able to do with the extra space is create a second VD across the disks.  This will be seen by the OS as a new/separate "disk" to use for storage.  Also keep in mind that, from the size of your RAID 5 you are probably using 73GB SAS drives, that you cannot mix SAS and SATA in the same array, so if you decide to replace the drives with larger ones, they MUST be SAS drives, not SATA. You could also add more drives - of any size, SAS or SATA - to your server and set them up as a new/separate VD/array to use for storage.    
   This server has perc5 and 3 hd totaling 208123mb.  we would like to add hard drives but are unsure if we can.  Is it possible to replace 2 of the existing and add another without losing data. or just add a 4th?  are we limited with perc5 to a particular size of drive?  Any help or advice would be tremendously appreciated
adding larger drives to poweredge 1900