Can't add hard drive to RAID1

[realdvk]

I have RAID1 storage pool of 2 hard drives. I want to add 3rd drive to this RAID1, but option is grayed out. Please provide instructions how to add 3rd drive to RAID1 storage pool.

[TMzethar]

Hi,
If you want to use the new disk as another identical redundant disk for RAID1 (with no change in total available space), sorry TOS does not support this usage.
For RAID1, we offer the option to migrate to RAID5 (increasing the space of one disk while maintaining the number of redundant hard drives at 1).

[realdvk]

But i am able to create 3xHDD new RAID1 from 3 blank drives. So the core feature is supported. Why no ability to "add" drives?
Is there an ability to request features?
I need 2 drives redundancy using 3 bays only.

[TMzethar]

We will verify the issue you have raised.

[TMroy]

But i am able to create 3xHDD new RAID1 from 3 blank drives. So the core feature is supported. Why no ability to "add" drives?
Is there an ability to request features?
I need 2 drives redundancy using 3 bays only.

With 3 drives only but 2 drives redundancy? This means only one drive works without any raid configuration. Technically, this is impossible.

[Gremlin]

But i am able to create 3xHDD new RAID1 from 3 blank drives. So the core feature is supported. Why no ability to "add" drives?
Is there an ability to request features?
I need 2 drives redundancy using 3 bays only.

With 3 drives only but 2 drives redundancy? This means only one drive works without any raid configuration. Technically, this is impossible.

Surely this is how the OS partition works? Multiple drives with RAID1 allows (multiple-1) redundancy.

[TMroy]

Oh yeah, use multiple drives to create a raid 1.