[Android]device layout partitions introduction

[Android]device layout partitions introduction

The flash space on an Android device typically contains the following partitions.

boot

Contains the Linux kernel and a minimal root filesystem (loaded into a RAM disk). It mounts system and other partitions and starts the runtime located on the system partition.

system

Contains system applications and libraries that have source code available on Android Open Source Project (AOSP). During normal operation, this partition is mounted read-only; its contents change only during an OTA update.

vendor

Contains system applications and libraries that do not have source code available on Android Open Source Project (AOSP). During normal operation, this partition is mounted read-only; its contents change only during an OTA update.

userdata

Stores the data saved by applications installed by the user, etc. This partition is not normally touched by the OTA update process.

cache

Temporary holding area used by a few applications (accessing this partition requires special app permissions) and for storage of downloaded OTA update packages. Other programs use this space with the expectation that files can disappear at any time. Some OTA package installations may result in this partition being wiped completely.

recovery

Contains a second complete Linux system, including a kernel and the special recovery binary that reads a package and uses its contents to update the other partitions.

misc

Tiny partition used by recovery to stash some information away about what it's doing in case the device is restarted while the OTA package is being applied.