I have a FAS 2520 in 7-Mode with 12x900GB disk and two controllers. After system setup, I've realized that each controller has 6 disks (3 for aggr0 and 3 spare disks) and I can't create new aggregates because there aren't enough spare disk. As I can't create new aggregates with this configuration, I'm thinking to change 2 spare disks from the Controller B to the Controller A, and add 4 disk to aggr0 in Controller A, leaving just one spare disk to each aggregate. I don't know if this configuration can be done, and if it's so, would I have High Availability if the Controller A fails? because I don't know either if volumes of Contoller A could be reach from Controller B when Controller A fails.
Anyway, what do you think is a good configuration to have high availability and not wasting resources?