By the way I have another small question, i see the available internal storage indication showing 14gb max.
Since I have the 16gb model, I guess there is some space occupied by the operating system? (sorry, propably has been asked many times!!)
It has to do with several things:
First, manufacturers of SD cards and hard drives are sort of sneaky when they say something is 16GB. For a long time, hard drives advertised as, let's say, 512MB were actually 512MiB (binary megabytes not decimal megabytes). Then, a long time ago one company figured out they could get away with reporting a MB or a GB as 1,000,000 bytes or 1,000,000,000 bytes, respectively. Pretty soon, the entire storage industry was forced to go along with this. However, this definition of a MB/GB is not the case in an operating system, where a MB or a GB have always traditionally been 1048576 bytes (2^20) and 1073741824 bytes (2^30), respectively. There was so much confusion after all this craziness, that MiB and MB are
now officially separate units.Second, there is a good amount of space reserved for the firmware partition, where the OS is held, as you already guessed. It includes ample room for future additions and upgrades.
Third, there is filesystem bookkeeping overhead for the main data partition (EXT4 filesystem). The filesystem needs to reserve and use space to keep track of all the complicated work it does, and this is especially so for modern journalling filesystems.
So, that is why you see less freespace available than you might think. Note that RAM manufacturers do not pull this trick. When you buy a 1GB RAM module you really are getting a device that can hold 2^30 bytes of information.