What is File System

Many say that programs and games are in the "memory" of the computer. This popular term was ridiculed and became very popular in the 90's among former gammers and computer beginners, since in the past games were co-related to cards and / or memory cartridges.

The concept in principle is not so wrong, after all there is still a "memorized" program somewhere, the mistake that occurs is that a computer, from the simplest to the most complex, uses various types of memory, and professionals area and / or regular users who have a basic knowledge, know how to distinguish that memory is where everything goes, but it is not, that is, it is an area where nothing is recorded forever, as it is lost.

The computer's real memory is a volatile electronic chip, containing microscopic transistors that explicitly depend on electrical energy to maintain a state, whether this state is "on" or "off", thus generating the bits in turn, 1 and 0 (zero ).

A transistor is an electronic component with three contacts, one of which is the feeder power (to make it work), the ground (negative) and the other which will receive the status of passing energy or not to continue the circuit, depending on the value you receive for the feeder energy.

Anyway, we will not go into details of engineering in its functionality, but memory as it is known in popular terms, is known physically as Hard Disk or Hard Disk.

This type of "memory" (or rather, disk) stores information on plates containing polarized iron filaments, where they can maintain magnetized states or not, and can keep the data for many years (as long as there are no problems with the disk arm [ we'll see this in a moment]).

In the images above, you can see the open and closed hard drives. Of course, the disc is always closed in a cover that does not allow dust to enter, since working with it open, it compares to an airplane at full speed walking at 5cm from the ground, that is, any dust, would be a catastrophe for the data being written or read.

A hard disk consists of an arm, disks that rotate through an engine that maintains a fixed speed, which can be 5,400 RPM (revolutions per minute), 7,200 RPM, 10k (rpm), 15k, 30k, among others. Of course, the most popular are currently 7,200 RPM for desktop disks, and 5,400 RPM for notebooks, and soon followed by disks also called "Raptor" from WDC (Western Digital Corporation - Manufacturer of quality hard drives), that reach rotation speeds of 10k and 15k in a single disk. Above that, they are disk clusters in storage (large data storage systems, usually located on the company's network) that simulate speeds by comparing the transfer rate by adding the speeds of the disks in the set.

A storage, or also known as SAN (Storage Area Network), is a place where it stores a lot of information in a safe, intelligent way, using the company's network, being transparent to any operating system and still manages to have speed.

Speed ​​is gained on the basis of multiple disks working in a set, but to ensure consistency in the data that is saved, it is necessary to have more disks so that the data can actually be safely saved faster.

The current storages work in margins of 30k (simulating a disk of 30,000 rpm) and 45k (45,000 rpm).

In practice, this speed of physical form, would be unable to write the data safely, but the file system of the system distributes the information among several discs so that it can have this gain in relation to the speed.

While a popular hard drive can record at a mere 80 Mb / s, storage can easily record over the network, from 400 Mb / s to 1 Gb / s, and depending on the storage, up to 10 Gb / s using a fiber- optics, but in this case, they are storages that have more than 150 hard drives inside.

As you can already see, a file system is a little complex to explain, as it involves several basic factors that you may never have read about, but this is the simplest of the principle.

A file system has several compositions, layers, and applications.

A computer (based on x86 architecture), starts its operation through the BIOS (Basic Input and Output System) (or for retarded people: "Ignorant Bug Operating System"), which in turn, starts its operations to read the local hard disk of the machine , in the first channel of the first disk controller, obtaining the zero track information of the disk.

The hard disk has software on the zero track, which loads the file system program into RAM (Random Access Memory), and with this, the computer and the computer's processor, understand its partitions and their structure, loading the rest of the components as you read the operating system settings files, logs, and the file system file table for loading a computer's operating system.

The file system consists mainly of software, a micro-code that is embedded so that the computer system and the processor know how to operate it, and a file allocation table, where all the metadata of a file so that it can be accessed on the recorded part of the disc. Generally, this file allocation table occupies 2.4% of the total disk space, that is, for every 1000 Mb formatted with a file system, 1024 Mb is used.

The file system can store data as its table allows to store this metadata. NTFS has a table with 256-bit entries, which allows the disk to be used with a formatted partition of up to 16 Eb (Exabytes), unlike FAT32, which operates in 32 bits and has a theoretical limit of 2 Gb The actual limit would be 4 Gb, with modifications to the system, and these modifications allow the system to be used with larger capacity disks, such as pen-drivers for cameras with 16 Gb capacities, and the camera can only work with FAT32. (This is because the size of the sectors are increased, and each file, however small, occupies a minimum pre-determined size in the system, but as cameras generally save large files, (larger than word documents for example) this limitation is not so seen by users.

NTFS-formatted flash drive works on a computer, but on devices like a car audio player or a DVD player, they don't understand this file system format, as it is a proprietary Microsoft system, and it has certain parameters of use and permission level that electronic devices should incorporate devices with high processing capacity to work with these discs.

Currently, on Linux, NTFS is already supported through paths, but it is not yet fully functional, for example, for data repair. Accessing NTFS on other systems can damage the file system, as it consists of a complex database system, using a file called the MFT (Master File Table), located at the root of the disk, hidden so that the user cannot view its contents or access to be able to view, however it is not allowed to save anything with the name "mft" at the root of the disk, without having an extension for such a file, as this could overwrite the entire file system, "deleting "all system data.

"Erasing" with quotes, because all the disk formation in windows, this is exactly what it does. It deletes this file which contains the record of the information of the saved files, and does not physically delete it from the physical disk, as with low-level formatting (which passes several zeros and ones across the entire disk so that it is actually completely deleted).

Physical formatting does not recover Bad Blocks (allocation areas damaged by reuse and wear, since it is a magnetic medium, has read / write / rewrite limitations on it).

In Linux, there are several file systems, one more complete than another, others simpler, others more centralized, in short, they all perform the same function: store files.

As the files are stored, it is a matter of the file system to manage and treat them.