If its just data (as opposed to the OS) , at 300GB you could use rsync to make a "mirror" of your data to cheaper larger sata drives. With USB3 you can now do it to external devices 
Hi all, I have a server with two 300GB HDD using Raid 1 , set up Centos 06. I want Backup full Server to a Different Server ( or Cloud Server , or diifferent HDD) . How do this ?  
Backup full Server Centos