AX4-5 Adding new disk

Bonjour (Hi),

I want to add a new disk in an AX4-5.

I just want to know if i could add this disk to an existing RAID GROUP and and this new capacity to an existing LUN.

I've got Navisphere Express.

To add a disk to an existing raid Group i think it's not a problem, but to add capacity in an existing LUN i need to make a META-LUN or to use virtual provisionning, no ?

Thank you.