i am lookign to set up freenas on a older P4 pc with 2gbs of memory and 4x3tb seagate sata drives. The only problem i have is i only have 3 blank 2tb drives. 1 of the 4 has media that i use to stream to my raspberry pi xbmc pc. The end result is to have a raid 5 set up with the most harddrives my motherboard will support so i can stream to my pi. am i able to create a raid5 setup with the 3 blank ones then copy my data over from the 4th and when that completes install the 4th and expand the array to cover all 4 drives? with out losing any thing?