Check disk space, Android explain each directory

df
Filesystem Size Used as Free blksize
/ dev 2.0G 2.0G 116.0K 4096 ---------- contains all Linux external device used in the system
/ sys / fs / cgroup 2.0G 0.0K 2.0G 4096-- ------- any process of Linux kernel functional grouping of management. Android operating system will by virtue of this technology, assign a different cgroup for each application, each program will be isolated, to achieve the purpose of an application without affecting other applications environment.
/ mnt 2.0G 0.0K 2.0G 4096 ---------- directly understood as "mount" to mount the drive, directory of your USB device
/ system 1.9G 1.5G 503.5M 4096 ------- - that we brush partition ROM. . . Andrews system directory, which is stored are system files
/ cache 122.0M 1000.0K 121.0M 4096 ------------- cache partition is
/ metadata 11.7M 40.0K 11.7M 4096 ---- ------------ one pair of current workspace configuration records
/ data 18.3G 806.5M 17.5G 4096 ------------ partition is what we install APK district
/ oem 7.9 1.3G 6.5G 4096 G
/ Storage 4096 2.0G 2.0G 0.0K
/ mnt / Runtime / default / emulated 18.3 g of 806.5M 17.5G 4096
/ Storage / emulated 18.3 g of 806.5M 17.5G 4096
/mnt/runtime/read/emulated 18.3G 806.5M 17.5G 4096
/mnt/runtime/write/emulated 18.3G 806.5M 17.5G 4096