Why does Ubuntu not let me write anything if the partition has less than 5% free space?

Question

ubuntu

Actually, subject.
I would like to understand why this is happening, Why is this done? Is it possible to decrease this threshold? Because my 16 Terabytes - 5% is quite a lot.

Answer 1

When creating a file system by default, Linux reserves 5% for unspecified needs of root.
Log in as root user and you can fill in the rest of the free space.
An example of how you can fix this:
PS But it's better for the root user to leave at least a little reserve.

Answer 2

This space is reserved for the needs of VIPs - programs running with superuser rights. This is a pretty reasonable decision, because. they often need to urgently write down something important.
In addition, when the disk is full, its performance decreases.
On HDD - due to file fragmentation.
On SSD - file fragmentation is not dangerous; on the other hand, the SSD firmware begins to experience difficulties with remapping sectors, and this is necessary to reduce the wear and tear of flash memory.
So the developers did everything right. On FreeBSD this has been practiced for a long time.