Why Low Space For App Installation? Understand Android Partitions
Many complain about Android, especially in low end devices which comes with limited memory available to install applications. And this complaint is quite justified. If I have a phone of 512 MB ??of space, why really I have only 100 MB to install applications? Why does it say that in the internal memory is only 192 MB of space?
The key to all this are the partitions. Internal storage for Android is divided into multiple partitions, and we can use only that which is reserved for data, which also has to live with all the space used by applications to store data and also the operating system. We will see in detail what these partitions are.
Android partitions are named as Unix operating systems, since Android is based on Linux. So they do not use letters as in Windows, but you have to use special commands for viewing on your mobile phone.
/Boot : This partition contains the information necessary to boot the Android phone . Includes bootloader and Linux kernel. Without this partition, device is unbootable. When you install a ROM, data are replaced with new ones this partition.
/Recovery : This partition contains an alternative /boot. If you start here, you have access to the console and can perform certain advanced tasks, especially if you install a different recovery program that is districuted in the name of ClockworkMod. We can perform tasks like: Erase all data on the terminal, install an update or a new ROM . Many advanced features, like having a recovery than the one factory, needs your device to be rooted.
/System : This partition contains the operating system (except the kernel and bootloader) and the applications that come by default in the terminal. If you delete the contents of this partition, the phone does not boot. Of course, we can always go into recovery and install a new ROM.
/Cache : Temporary Data of operating system. For example, here is where you download an OTA update before installing. You can safely delete the contents, which regenerate themselves. Learn more about Dalvik Cache and How to Free up space by Clearing Dalvik Cache.
/Misc : Contains important data about Device configuration. Careful handling.
/Data : Here you have downloaded applications and the saved data of application. For example, contain messages, contacts, emails from Gmail to the levels that you have completed on Angry Birds. Deletion of this partition would leave the terminal as it came from factory (Factory Reset). This is the partition which your Device consider when it says Free and Occupied space.
Here is where App2 SD comes to play. When /data is occupied completely, you can have external SD card mounted to your device and move applications there. Before that, you need to learn How to prepare SD Card for App2SD.
Why in-built Applications takes no space until Upgrade?
And here is the explanation of why the applications that come in built with device takes up no space. These applications, which come with the phone, take up space in /system (ie in /system/app). And therefore no space in /data which is the problem here.
Now, if an application update comes, for example Gmail, Google Maps, Google search, then they go on to occupy some space. This is because when these applications are updated, they begin taking up space on /data. These applications can not be uninstalled (without root), but uninstalling the updates, so the application will be reused is the one in /system, and no longer take up space in /data (except the data associated with execution).
With Ice Cream Sandwich, these are things of Past
With the Android 4.0 Ice-Cream Sandwich upgrade, this partitions aren’t necessary and can be avoided (if manufacturer wants to). Android 4.0 devices can operate with one partition, which stores all data of /data and /system in lower versions.
This is one cool feature which I didn’t mention in 5 things I liked about Android Ice Cream Sandwich because this has a drawback. You can not use the phone as mass storage. But we will discuss about it in detail in next article about Memory Management in Ice Cream Sandwich.