Hard disk drive (HDD)...

• Some time that is called hard drive, HD or HDD and this is a non volatile memory.
• HDD is a permanent data and information are store and retrieve.
• HDD is connect and power connection is power supply unit(PSU).
• The magnetic storage hard drive is based on a more than 40 year old technology and still is being improved repidly.
• Hard disk continue to shrink in size, gain increased storage capacity and increased transfer speed. whatsapp apk download
• The development has been tremendous during the last 10 year.
• The only the storage capacity is not decide the one hard disk is good than other one.the other factore requires for choosing good hard disk.the following factor needs to closely watch when we choose the hard disk. game killer

Structure of hard disk:

1.Disk platters:

• All hard disk consist of thin platters with a magnetic coating.They rotate quite fast inside a metal container.
• Data are written and read/write heads,which are designed to ride on a microscopic cushion of air,without touching the power.They register bits from the magnetic coating.

2.Spindle motor:

• The disk platters are connected to one central spindle,which is directly connected to the main spindle motor.Most of the spindle motor is located at the bottom of the drive.
• Spindle motor gives circular rotation to the platters for read/write operation on specific location.
• This motor work on a feedback loop to automatically adjust the disk rotation speed.

3.Read/Write head:

• The arms, which guide the movement of the read/write head , move in and out. These heads do not require clening or any other maintenance, as the floppy drive head.
• Because these head do not touch the disk surface insted it float a distance above the disk suface during the read/write process.

4.Head actuator mechanism:

• To moving read/write head disk drive on the platters referred as head actuator mechanism.
• There are to type:

          1.Stepper motor actuator 

          2.Voice coil actuator

5.Sides or head:

• Drive with three platters one read and write on six sides.
• If the drive is servo based than one side may be used;for the servo information and only 5 usable sides will be available.

6.Track:

• Each side of the hard disk drive platters surface is divided into concentric circles called tracks.
• These track are not visible marks on the disk surface instead these are magnetic infomation written during the formating of the hard disk drive.
• Each track is identified by its number.

7.Cylinder:

• The hard disk having more than one platter makes virtually a cylinder like structure on smae tracks of different platter.
• The data is store cylinder by cylinder on the disk.

8.Sector:

• The tracks are dividing futher, which called the sector.
• During the formatting of the hard disk,the formatting program divides the disk surface into different sector by writing magnetic platter on the disk surface.

Type of hard disk drive (HDD):

1.SCSI (Small computer system interface)

2.IDE (Integrated drive electronics) or PATA (Paralled advanced technology attachment)

          a)ATA IDE

          b)XTA IDE

          c)MCA IDE

          d)EIDE

3.SATA (Serial advance technology attachment)

4.RAID (Redundant array of independent drive)

5.USB (Universal serial bus)