Raspberry Pi_Eng_15.1.4 Review of Special Device

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15.1.4 Review of Special Device

15.1.4.1 Booting SD Card

The default Debian distribution consists of two partitions on the SD card. The first partition is 75 MB in VFAT format, a format for Microsoft’s removable devices. It has the files needed to configure Raspberry Pi and files to load Linux itself, and is mounted as “/boot” after booting. The second partition is much larger in the EXT4 format, the default format for fast access and data reliability in Linux. All other programs, user-installed programs, and user data are all stored here. It occupies most of the SD card.

Raspberry Pi_Eng_15.1.3 Mounting Device

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15.1.3 Mounting Device

15.1.3.1 Meaning of Mount

On Linux systems, all files used on the system are supposed to belong to a file hierarchy, one large tree type with root (/) at the top. These files may appear to be in one hierarchy, but may actually be scattered across a variety of devices.

Raspberry Pi_Eng_15.1.2 Formatting Disk

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15.1.2 Formatting Disk

15.1.2.1 What Is Formatting Disk?

After a partition is created for a disk, the partition must be initialized to a specific file-system, and this initializing process is format. When you format a partition, a specific file-system is determined for that partition, and a master directory is created that manages all the directorys and files that will be stored on that partition.

Raspberry Pi_Eng_15.1.1 Partition Management

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15.1 Management of Logical Storage Device

15.1.1 Partition Management

A disk can be divided into partitions that are spaces managed independently and divided logically. Partitions are also called “disk slices” or “disklabel”. The result of partitioning is managed by partition table in sector 0 of disk.

Raspberry Pi_Eng_15.0 Chapter 15 Storage Device and Filesystem

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Chapter 15 Storage Device and Filesystem

Chapter’s Main Topics

This chapter describes the basic concepts of storage devices used to store data and how to manage storage devices by partitions, and explains how the structure of the file system provided by the Raspbian operating system basically is configured.

It includes descriptions on the following topics:
■ Logical storage device

■ Partition management

■ Format disk

■ Mount devic

■ Structure of file system

Raspberry Pi_Eng_14.2.2 USB Device and Device File

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14.2.2 USB Device and Device File

14.2.2.1 USB Device and “/dev” File

A USB device is a bus type device. In Raspberry Pi system, USB device is managed by “/dev/bus/usb” folder. If you look inside the 001 folder, you will see the following files. File names are in the form of 001 ~ 016, which means the device number of USB device. You can see that you have a one-to-one correspondence with the USB device that you inquired before with the “lsusb” command.

Raspberry Pi_Eng_14.2.1 “lsusb” Command – Confirm USB Device

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14.2 USB Device

14.2.1 “lsusb” Command – Confirm USB Device

You can use the “lsusb” command to see what USB devices are installed in Raspberry Pi system.

Raspberry Pi_Eng_14.1.4 Network Device

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14.1.4 Network Device

14.1.4.1 Characteristics of Network Device

In Linux, a network device is thought of as an entity that sends and receives data packets. A network device is usually a physical device, such as an Ethernet card. However, there are some network devices defined with only software, such as loopback device that is used to send data to itself.

Raspberry Pi_Eng_14.1.3 Block Device

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14.1.3 Block Device

14.1.3.1 Block Device Characteristics

The block device inputs and outputs data in unit of block when processing data in the device, and increases the processing performance by placing a intermediate buffer.

Raspberry Pi_Eng_14.1.2 Character Device

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14.1.2 Character Device

14.1.2.1 Charateristics

The character device is the simplest of all Linux devices, and it inputs and outputs data in character unit when processing data in the device, and there is no intermediate buffer.