Hard disk basics and use in Linux systems

hard disk related basic concepts:

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each disc of the hard disk is the upper and lower two disk faces, each disk surface can store data becomes the effective disk surface; because there is a corresponding read/write head on each of the effective discs ( Header ) , so the panel number is also known as the magnetic number one; all discs (heads) from top to bottom from 0 start numbering;

     disk is divided into concentric circles when formatted, and these concentric circles are called tracks ( track 0 track, the storage of hard disk data is the beginning of the outer ring;       

Each circular track is cut in such a distance to form an arc of equal length, and each arc is a sector ( Sector ) ; sector is from 1 starting numbering, the data in each sector is read out or written as a unit, that is, a sector is the smallest unit of read and write (because the head can only be positioned at the beginning or end of a sector, not within the sector);

The same track on all disks, forming a cylinder in a vertical direction, often called a cylinder ( Cylinder ) ; The cylinder is the same as the track, also from the outer ring to the inner ring, from 0 start numbering;

     cylinder ( Span style= "FONT-FAMILY:CALIBRI;" >cylinder hearder Span style= "font-family: ' The song Body '; >), Sector ( sector chs chs address;

number of heads ( Headers ) indicates that the hard disk has a total of several heads, that is, several platters, and the number of cylinders ( Cylinders ) That also indicates that there are multiple tracks on each side of the hard disk; number of sectors ( Sectors ) indicates how many sectors are on each track, and each sector is typically 512B ; so Maximum disk capacity based on CHS Addressing method =heads*cylinders*sectors*512b

The robotic arm (the head arm) moves the head to the corresponding track (where the data is located), which is the process of selecting the cylinder, that is, the process of seeking the path , stopping at the beginning or end of a sector, the disk continues to rotate, and waits until the process of turning to the sector where the data to be found is called the wait time , the waiting time for all data, called the average seek time , is also known as the average wait time.

Example: System ( CentOS6.4 ) information for the disks displayed in the

[[email protected] ~] #fdisk  -ldisk /dev/sda:160.0 gb, 160041885696 bytes255  heads, 63sectors/track, 19457 cylinders     #255个磁头, 63 sectors per track, 19,457 Cylinder units = cylindersof 16065 * 512 = 8225280 bytes        #Units为每个柱面大小 =255*63*512sector size (logical/physical):  512 bytes /  512 bytes      #每个扇区的大小I/o size (minimum/optimal):  512 bytes  / 512 bytes          #磁盘的IO读写单位Disk   identifier:0xc82f4e59   device boot      start          End      Blocks  Id   System/dev/sda1   *          1        &nbSp;  64      512000  83  linuxpartition 1  doesnot end on cylinder boundary./dev/sda2               64       19458   155777024   8e  linux lvm

usually a piece of hard disk Linux can be used within the system, to go through the steps: Create a partition à Formatting à Mount , using command tools, respectively Fdisk-->mke2fs-->mount to achieve.

* * Reference book "Big Store"

This article is from the Zebra Linux blog, so be sure to keep this source http://zebralinux.blog.51cto.com/8627088/1547861

Hard disk basics and use in Linux systems