The system disks section shows the status of the system disks, and their current usage. The BUI displays this with a pie-chart, and the CLI as a text list. For example:
hostname:> maintenance system disks show Properties: profile = mirror root = 1.14G var = 52.4M update = 2.52M stash = 14.8M dump = 16.0G cores = 18K unknown = 39.0G free = 401G Disks: DISK LABEL STATE disk-000 HDD 7 healthy disk-001 HDD 6 healthy