[blue68f100]

Haven't worked on a 520, but with the 4500 you have the array completed removed before upgrading the HD's. So with the unit in a as received state (clean install). You only have drive 1 in, cold boot the unit with the new HD in drive 2 position. The OS will transfer the OS (takes <7min), power down and remove Drive 1 (orig) and swap drive 2 to 1 position. The boot the unit. Once up you can then hot swap the remaing drives 2,3,4.

With you installing new drives with the array built, it thinks it only needs to use 250gig HD's. You need to envolk the recovery console. From there It will give you a option to do a clean install wipping the arrray clean of all previous history.