It does not matter that you have a device with a memory from 32gb, sooner or later you will clash with the problem of the space for applications exhausted, this because the MIUI has a management of the divided archive that in fact limits application space.
For example, on a Xiaomi MI2 or MI2S from 32 gb the memory dedicated to the containment of the applications is "only" 3,75gb and 25gb remains for the data. The other missing 3 / 4gb are invisible and dedicated to the operating system.
If those 4gb seem few, but you have to consider that the app use that partition exclusively for the files needed to run, while any additional data are supported in the largest memory. For example, the browsers will install the program files in small memory and the (gigantic) maps in the larger memory. In general we should be able to install at least 200 applications around without any problem.
In the long run, however, a problem takes over: the space runs out despite having installed a few applications / games. In fact, the uninstalled applications leave orphaned files, the cache of programs grows out of proportion and the playstore archives "unnecessarily" a considerable amount of backup data and in fact the on the report in Settings-> Memory the space available in addition to that of applications will not coincide with the total available. And here it will begin to receive an "out of space" error by installing or updating our programs.
And this is where the function comes to our aid Cleaning application Safety present from MIUI 3.11.15.
Once the Cleaning function has been started, we will be in front of a Home that consists of 5 sections: Cache, Advertising files, Packages, Residuals and Advanced (top right). It is possible to perform a complete scan of the system or face each single section individually as I usually do.
In this section we will be allowed to clean the cache created by the system, by the themes and by every single application. The cache is essentially the set of temporary files that are created the first time you start functions and applications and make it easier to start and run. Here you will find much of the lost space and you should not be afraid to delete it because the cache, if needed, will be recreated the next time the application is started. Since often not all the stored cache is more necessary, it is very useful to do some cleaning every now and then.
By default, some items are not checked, such as google maps, the song database and the whatsapp archive. If you do not know where to put your hands, as usual, leave the settings as you find them and proceed! [Clear]
In this section you will find any identified advertising files: banners, pages, etc.
You can erase everything in peace but unfortunately it's rare to find large files, so for space recovery this section is often useless. [Clear]
This section basically hosts all the apk (installation files) that are found in storage memory only. For example, if you have downloaded some apk to the download folder, you will find it in this report. It comes from the fact that often there will appear almost exclusively personal files that you probably want to keep and in fact even the system will tend, by default, to deselect most of the items. Being a .apk file, there are several megabytes at stake but deleted only if you are sure you do not need those installations anymore. [Clear]
The section Advanced, subdivided further into 3 voices: Cache, Residual, Large Files. The first two are homologous to those in the main home while Large Files it's a crucial function to understand where all the lost space is finished. In fact, Android, for applications that support it, keeps a backup file of the previous version so you can restore it in case of need. These files have the extension .bak and are listed along with other "large files", such as video, mp3, etc .. which instead can be left out or evaluated individually. These old versions, being apk files they have a considerable size and eliminating them will give a nice breath of air to the phone's memory. [clear]
By summarizing, by cache cleaning (but with time will be partially recreated) and removing backups of older versions (.bak file) we will recover a lot of space by consistently improving the situation.
[alert-warning] This statement has been tested on Xiaomi Mi2 and M2S 32gb but it is applicable to all MIUI-mount terminals with a similar division of partitions: one for the system and one for the data. [/ alert -Warning]