Linux : How to reduce the percentage of reserved blocks on ext4 filesystem

By | October 13, 2022

By default, ext4 formatted drive will automatically reserve 5% of the allocated space for root user, which reduce the total available space for other users or the application you may want to use that drive for.

This 5% ratio make sense on small volumes and purposes like the root (/) filesystem, but does not make any sense for a fileserver volume of 10 Tb.

Fortunately, this can be change easily and without any data loss using the following command :

The “-m” option represent the percentage value you’d like to set the percentage of reserved blocks.

To completely disable the reserved space for root user, use “0” :

To change the reserved blocks percentage to 1% :

Below you can see the difference between the default 5% of reserved blocks VS 1% :

10Tb drive ext4 formatted with default 5% reservation

10Tb drive ext4 formatted with default 1% reservation