Ext4 reserves five-percent of the filesystem's available space by default

By default, Ext4 reserves 5% of the filesystem’s block count for the super-user, so that root processes can continue to run without problem even if other non-privileged processes are prevented from writing to the filesystem when it’s full. This makes perfect sense for the root partition where the operating system is installed, but for most other partitions, reserving 5% of the disk space for the…