A área cinza escuro é de 5%, reservada para processos privilegiados. Para uma explicação detalhada, veja abaixo.
Altereovalorvia
$sudotune2fs-m2/dev/sdd1tune2fs1.42.12(29-Aug-2014)Settingreservedblockspercentageto2%(38394blocks)
evejaadiferença
de man tune2fs
-m reserved-blocks-percentage
Set the percentage of the filesystem which may only be allocated by privileged
processes. Reserving some number of filesystem blocks for use by privileged
processes is done to avoid filesystem fragmentation, and to allow system
daemons, such as syslogd(8), to continue to function correctly after non-privileged
processes are prevented from writing to the filesystem. Normally, the default
percentage of reserved blocks is 5%.