Чтобы не забыть о старых ошибках.

#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%.

Некоторые последствия вынужденных шагов легко объясняются маном. А ведь надо было раньше об этом думать, да...