Analysis of the Principle and Method of Implementing Linux Disk Partition

remember:

IDE disk: the first disk is hda, the second disk is hdb...

The first partition of the first disk is hda1, the second partition is hda2...

SAS/SATA/SCSI disk: The first disk is sda, the second disk is sdb...

The first partition of the first disk is sda1, the second partition is sda2...

The general partition is located at /dev/sda1.

What is Partitioning

Disk partitioning is equivalent to partitioning the disk.

Disk partition type

1. Primary partition (primary) P

1) The partition that must exist in the system, the system disk selects the primary partition for installation

2) The digital number can only be 1-4. sda1, sda2, sda3, sda4

3) The number of primary partitions is at most four and at least one.

2. Extend partition E

1) Equivalent to an independent small disk. Independent partition table cannot exist independently.

2) Have an independent partition table.

3) Cannot exist independently, that is, cannot store data directly

4) Logical partitions must be created on the extended partition to store data

5) The total number of primary partitions (primary partition + extended partition) occupied is up to 4

3. Logical partition (logic)

1) The numbering can only start from 5

2) Stored on the extended partition

3) Store any common data

Disk partitioning method

①1~4 primary partitions

② There can be at most one extended partition, and 2 ≤ extended partitions + primary partitions ≤ 4

How disk partitioning works

Disks are partitioned by cylinder. (Increase reading and writing speed)

Where disk partitions are registered: disk partition table. (Stores partition result information, location: track 0, head 0, sector 1)

The first 446 bytes of a sector (system boot information), followed by 64 bytes (partition table), and the last two bytes (partition end mark).

A partition information occupies a fixed 16 bytes, so there can only be 64/16=4 partitions.

The key to disk partitioning is to modify the 64-byte partition table.

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