Stop receiving "Your disk is almost full" notification

"without any serious performance degradation"

It is not so much about the performance. It is about the "wear levelling" that is in modern SSD controllers. This is about lifetime pf the ssd. The more free space the longer the lifetime, and the less loss of living "cells".

Thanks so much - that made my day. We were invited by another Munich native (I met her many years ago here), her extended family and some in laws (from Poland) which made for some very interesting conversations..

Perfect! Just help me turn it off, I don´t need someone to advice me to free up more space, buy another HD, buy another computer, move to Mars, etc

Drew, when this warning is coming up on systems that have 10+ GB free space; then it is the warning system that is wrong. OSX can work just fine with as little as 1 or 2 GB of free space, regardless of what Apple says.

As for the threshold settings for that warning to come up - It's clear that you haven't spent any time under the hood of any Unix, Linux, or DSB based operating system. There is certainly a setting somewhere in one of the system files that tells OSX at what point it should display the warning dialog.

The question is simply which file is that, and how to edit it?

Free up some space on your drive, it is dangerously low at the moment.

Have it your way the, I am to going to argue with you.

I get that annoying XP/Vista-ish notification when I have 75GB+ free.

When that message appears, it should not be ignored. The only way to stop it from appearing is to increase available storage space so that your Mac can continue to work normally. To learn how to do that please read macOS Sierra: Increase disk space.

macOS "Sierra" offers additional options for offsite storage. Please read Free up storage space on your Mac - Apple Support.

Apple have always recommended you have more free space than you seem to think is OK, this one is from 10.8…

OS X Mountain Lion: If you see a gray screen at startup

…make sure your computer has at least 1 GB of memory and 9 GB of available disk space.

Os's do not need fewer resources over time, they need more.

You need to heed the warning that the OS is throwing at you. Eventually you can lose data or get into an unbootable state. That is why there is no option to turn off the dialog.

You could be better off fitting a larger disk compared to looking for ways to circumvent the warning if the Mac supports user replaceable storage. Post the model info if you want help with that but the answer to this problem is the one that you do not want to hear – remove some data.

There has to be a way to turn off this annoying notification. there is nothing wrong to use the disk that I bought to its full potential.

Also people responding like "just clear some space out" you guys are just as annoying as the notification. There is a clear question to how to turn off a boolean value to stop this notif to appear.

Apples OS disagrees with your opinion — tell them your feelings on the dialog…

http://www.apple.com/feedback/

The 'defaults system' should contain the setting you claim exists, there are commands to search for functioning values…

https://developer.apple.com/legacy/library/documentation/Darwin/Reference/ManPag es/man1/defaults.1.html

Unfortunately no sites have a setting listed for the disk full dialog (probably because it does not exist).

http://www.defaults-write.com, there are many others that list defaults values for OS X.

It is anoying to you because you are wrong and the answer is to free some space. Take it to an Apple Store as you clearly do not believe the sound advice already given here.

macOS is a UNIX operating system, and needs 10 - 12% of total storage for the operating system to function properly — over and above swap space. Those messages that you want to turn off are from the operating system itself telling you that you have dipped into its reserved space requirements. There will be no turning those messages off until you free up sufficient storage.

This was true 25 years ago with multiple, other UNIX solutions too, and the same customer advice to free space has not changed since.

I'd love to see a screenshot of the annoying pop-up message about low disk space on UNIX 25 years ago.

OP did not request customer advice. Direct question with direct answer: OSX does not allow you to disable the notification.