Implications of Thick Volume Occupying 93% Of The Storage Pool on QNAP NAS

Spoiler Alert: I don't know a ton about what I'm doing, but I've been tasked with data protection and backing up at my workplace so I installed a NAS and set it up. Ideally I'd like to not have to think about it all the time, and that means getting a lot of storage so I don't need to frequently replace the drives. SO I set up the storage pool to be the majority of the space and when I did that I got a warning that the volume should not be more than 80% of the pool. why is this? I changed that warning threshold to be 95% so I don't have to see any warning text, but I am wondering why 20% of the space is recommended to be reserved by default.

Thank you

I got a warning that the volume should not be more than 80% of the pool. why is this?

This is expected for Thick Volume in Storage Pool. Thick Volume always reserve Storage Pool space when it is created, even before it is used.

80% threshold warning is only to remind you that your Storage Pool is nearly full, and you may want to audit your Storage Pool usage or add new disks into your Storage Pool, that's why you can reconfigure it, e.g. to 95% in your case.

Maybe better case for this threshold warning is when your volumes are Thin Volumes, that you can over-allocate over your current Storage Pool. This threshold warning will remind you to audit your current usage or add new disks before your Storage Pool is full.