It means you have the dual-controller setup & these three disks are owned by the other controller.
So it looks like it has been configured for an 'active-passive' tandem where the controller you are looking at does the actual job, whilst the partner owns minimum number of disks (3) and take ownership only if the controller 1 fails.
The other option is to split disk ownership more or less evenly & run some workloads on both controllers.
Filer View dispalys disks which are owned by controller which you logged (data, partity, dparity, spare), and disks owned by second controller (partner). If you logon to second controller you will see that 0c.00.2, 0c.00.4, 0c.00.6 are data, parity parity, others are partner disk.