Linux host planning and disk partitioning

Disk Composition: Disc, robotic arm, head, spindle motor. The data is written on the disc.

The disc can be subdivided into sectors and cylinders. Each of the sectors is 512bytes.

The hard disk includes multiple disks, and the smallest unit of each disk is the sector. The sector makes up a circle and becomes the track. The magnetic column is made up of the same track on all the disks, and the magnetic column is the smallest unit of the split drive.
A cylindrical surface consisting of a magnetic column is a cylinder.

　　　　　　　　　　　　　　　　　　

Note that the first sector of the entire disk is important, and it records important information about the entire disk. These include:

Master boot Record, MBR: Where the boot loader can be installed, there are 446bytes

Partition table (partition table): Record the state of the entire hard disk partition with 64bytes

MBR is very important , because the system will be active to read the contents of the block when booting, so that the system will know where your program is placed and how to boot. If you install a multi-boot system, the management of the MBR is very important.

The partition table is the information that your hard disk partitions. Partition table in the 64bytes capacity, a total of four sets of record areas, each group recorded the beginning and end of the section of the cylinder number.

In a partitioned table, only four sets of partition information can be written

Divided into primary partitions and extended partitions.

The smallest unit of a partition is a cylinder

Extended partition : The purpose of this is to use additional sectors to record partition information. Partitions that continue to be separated by extended partitions are called logical partitions.

Features: Primary and extended partitions up to four (hard disk limit), extended partition up to one (operating system limit), logical partition is the extended partition continuously cut out the partition, logical partition of the device name number starting from 5th .

BIOS and CMOS

CMOS is a memory that records various hardware parameters embedded in the motherboard, the BIOS is a firmware written to the motherboard (firmware is written to the hardware above a software program), this BIOS is the computer system when the boot

The first program that will automatically go to the active execution.

To put it simply:

BIOS: Boot active firmware, will know the first device to boot

MBR: The primary boot partition block in the first sector of the first bootable device that contains the boot loader

boot loader (boot loader): a software that can read the kernel file to execute, the boot program can be installed in addition to the MBR, but also install the sector in each partition

Kernel file: Start the operating system function

Boot loader task: Provides menu, can choose different boot options

Load kernel files: Direct point to the bootable program section to start the operating system

　　　　　　　　　　transferred to other loader. The boot program can also be installed in the boot sector (boot sector) for each partition, in addition to starting the MBR installation. (Bird's private dish P73)

Why does a multi-system installation require Windows to install Linux first?

Because Windows is installed, its installer will proactively overwrite the MBR and the boot sector of its own partition, and you won't have a chance to choose. While Linux is installed, you can choose to install the bootloader in the MBR or the individual partition of the boot sector, Linux loader can manually set the menu.

Mount: using a directory as an entry point, the partition's data is placed in that directory, that is, access to the directory is the meaning of the partition can be read. The directory that is mounted is called a mount point.