In Centos 7 I see this (virtualized machine on a IaaS):
root@hongo developer]# fdisk -l
Disk /dev/vda: 42.9 GB, 42949672960 bytes, 83886080 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk label type: dos
Device Boot Start End Blocks Id System
/dev/vda1 * 2048 33554431 16776192 83 Linux
/dev/vda2 33554432 41943039 4194304 82 Linux swap / Solaris
[root@hongo developer]# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/vda1 16G 4.3G 11G 29% /
devtmpfs 3.9G 0 3.9G 0% /dev
tmpfs 3.9G 0 3.9G 0% /dev/shm
tmpfs 3.9G 65M 3.8G 2% /run
tmpfs 3.9G 0 3.9G 0% /sys/fs/cgroup
tmpfs 782M 0 782M 0% /run/user/0
tmpfs 782M 0 782M 0% /run/user/1000
Why I see only 11G reserved to / ?