Volume's usable space

Hi all,

I am an end-user of Netapp storage.

At my company, my area purchased 432TB of Netapp storage.

Our storage team has taken the disks, and now deployed/installed, and now of the 432TB storage, 37 has been set-aside for spare disks, and 70TB has been reserved for 'Netapp Health'. They say it is industry standard for array health and performance to carve out ~20% to provide capacity for background and OS processes.

This question is coming from me -- an end-user.  I am not a storage expert. I did try to understand this:

https://kb.netapp.com/support/s/article/ka21A0000000gB5QAI/faq-how-is-space-utilization-managed-in-a-data-ontap-san-environment?language=en_US

question please:

20% space reserved for Netapp health, to me, seems like a sizeable chunk of space that unfortunately my area cannot take advantage of as useable space. What is Netapp doing behind the scenes to require this amount of disk? I mean, is this space being used as scratch/temp space, during Netapp compression executions? Or perhaps for Netapp deduplication?  I am simply curious as to the details here. Again I am not a storage expert, I hope you can break it down for me!!  Thanks all!!