Android File Systems

Android Tutorials - Herong's Tutorial Examples

∟Android 5.1.1 Emulator File Systems

This section describes file systems used by the Android 5.1.1 emulator system. 9 file systems are supported in the Android emulator: /dev, /sys/fs/cgroup, /mnt/asec, /mnt/obb, /system, /data, /cache, /mnt/media_rw/sdcard, and /storage/sdcard.

Like any Unix systems, storage devices are organized as file systems. On the my Android 5.1.1 emulator, I can see the following file systems using the "df" shell command, which return disk space usages of file systems:

C:\local\android-sdk-windows\platform-tools>adb shell

root@generic:/ # df
df
Filesystem               Size     Used     Free   Blksize
/dev                   242.9M    24.0K   242.8M   4096
/sys/fs/cgroup         242.9M    12.0K   242.9M   4096
/mnt/asec              242.9M     0.0K   242.9M   4096
/mnt/obb               242.9M     0.0K   242.9M   4096
/system                541.3M   363.9M   177.5M   4096
/data                  541.3M   158.0M   383.3M   4096
/cache                  65.0M     4.3M    60.7M   4096
/mnt/media_rw/sdcard    31.5M     3.2M    28.3M   512
/storage/sdcard         31.5M     3.2M    28.3M   512

The "mount" shell command tells me how file systems are mounted into the file hierarchy:

C:\local\android-sdk-windows\platform-tools>adb shell

root@generic:/ # mount
mount
rootfs / rootfs ro,seclabel,relatime 0 0
tmpfs /dev tmpfs rw,seclabel,nosuid,relatime,mode=755 0 0
devpts /dev/pts devpts rw,seclabel,relatime,mode=600 0 0
proc /proc proc rw,relatime 0 0
sysfs /sys sysfs rw,seclabel,relatime 0 0
selinuxfs /sys/fs/selinux selinuxfs rw,relatime 0 0
debugfs /sys/kernel/debug debugfs rw,relatime 0 0
none /acct cgroup rw,relatime,cpuacct 0 0
none /sys/fs/cgroup tmpfs rw,seclabel,relatime,mode=750,gid=1000 0 0
tmpfs /mnt/asec tmpfs rw,seclabel,relatime,mode=755,gid=1000 0 0
tmpfs /mnt/obb tmpfs rw,seclabel,relatime,mode=755,gid=1000 0 0
none /dev/cpuctl cgroup rw,relatime,cpu 0 0
/dev/block/mtdblock0 /system ext4 ro,seclabel,relatime,data=ordered ...
/dev/block/mtdblock1 /data ext4 rw,seclabel,nosuid,nodev,noatime,nom...
/dev/block/mtdblock2 /cache ext4 rw,seclabel,nosuid,nodev,noatime,da...
/dev/block/vold/179:0 /mnt/media_rw/sdcard vfat rw,dirsync,nosuid,no...
/dev/fuse /storage/sdcard fuse rw,nosuid,nodev,noexec,relatime,user_...