All my servers have an 8 GB empty file on disk
In the mid nineties I worked in a research institute. There was a large shared Novell drive which was always on the verge of full. Almost every day we were asked to clean up our files as much as possible. There were no disc quota for some reason.One day I was working with my colleague and when the fileserver was full he went to a project folder and removed a file called balloon.txt which immediately freed up a few percent of disk space.Turned out that we had a number of people who, as soon as the disk had some free space, created large files in order to reserve that free space for themself. About half the capacity of the fileserver was taken up by balloon.txt files.