What Is Hard Disk Drive (HDD)? – POFTUT

What Is Hard Disk Drive (HDD)?

Hard Disk Drive is computer hardware used to store different type of data like a file, folder, image, video, office documents permanently in a computer. Hard Disk Drive may have different names like Drive, Hard Drive, HDD, Disk etc. In computer terminology, Hard Disk Drive is named as secondary storage.

Types Of Hard Disk Drives

Mainly there two types of Hard Disk Drives according to their internal design and price/performance.

  • Mechanical or Classical Disks contains a plate where data is stored. This plate is spun and data is read with the stick from the plate.
  • Solid State Disk (SSD) contains flash cells where data is stored completely in electrical states. There is no mechanical part running in SSD’s.

Mechanical or Classical Disk

Mechanical or Classical Disks are developed long type ago. Most of the computers run these type of Hard Disk Drives. They are named as Mechanical because they have running parts.

Mechanical or Classical Disk

Mechanical or Classical Disk

We can see that there is a stick which is on the plate. Data will be read or written to the plate by this stick. The plate is spun with a rotator which is connected from the center of the plate.

Rotate Per Minute – RPM

As Mechanical or Classical disks are spun with a rotator this will be related with the performance of the disk. Higher spin speeds mean higher performance. Spin speed is named as Rotate Per Minute. This means how many times a plate will rotate in a minute. This is called simply RPM. There are following RPM values for disks.

  • 5400 is the slowest RPM in modern disk drives. This RPM Disk Drives are used in energy-efficient systems like Laptop
  • 5900 is a special RPM
  • 7200 is very popular RPM rate which is used in PC and high-performance Laptops
  • 10000 RPM is generally used in enterprise hard disk drives like servers
  • 15000 RPM is a high-end enterprise disk drive
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Solid State Disk

Up to ten years ago Mechanical Disks were popular but a new type of Hard Disk Drive named Solid State Disk or SSD is invented. SSD works like Flash Memory and does not have a mechanical part. SSD is faster because there is no need to rotate a plate. Especially write performance or IOP’s are far better than classical disks. SSD’s were pricy but in recent years their prices are dropped and became cheaper.

Solid State Disk

Solid State Disk

SSD Cached Disk Drives- SSHD

We have learned that there are two main types of Hard Disk Drives name Mechanical and SSD. Mechanical Disks are cheap but their performance is lower. SSD is very performative but their prices a higher. Disk vendors have created the Hybrid of the SSD and Mechanical Drive which is named SSHD. SSHD contained both of the disk types where 8, 16,32 GB SSD with 500, 1000, 2000 GB of Mechanical drive. Data writes and reads are stored on the SSD part and then synchronized with the mechanical drive. Simply the data is cached to the SSD before reading and writing to the Mechanical Drive.

Hard Disk Drive ConnectionTypes

Hard Disk Drives are connected to the main board of the system. There are different types of connections which are developed during the history. Here is one of the most popular of them.

  • ATA or IDE is a very old connection type and protocol where transfer rate of 100 MB/s can be reached. It is superseded by the SATA connection types
  • PATA is a bit different version of ATA where Parallel lines are used to increase transfer rates
  • SATA is the new era of connection type where 3 Gb/s data can be transferred from the disk
  • SATA2 is the newer version of the SATA where 6 Gb/s data can be transferred
  • SCSI is used in enterprise hard disk drives where it provides stability. SATA disks can be connected to the SCSI disks.
SATA Connector

SATA Connector

Hard Disk Drive Sizes

Hard Disk Drives can be in different sizes. Especially in the ancient time disks were very big. But today with the help of nano and flash technology disk sizes are very decreased. Mainly following Hard Disk Drives Physical sizes are used in IT.

  • 2.5 Inch is used in mobile, low performance or density required systems. These disks are used in Laptop, TV, Modem, Firewall or Servers with a lot of disks
  • 3.5 Inch is used in Desktop or PC systems.
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Hard Disk Drive Capacities

Hard Disk Drives may have different storage capacities. Har Disk Drives supports the following storage capacities.

  • Less then 500GB
  • 500 GB
  • 750 GB
  • 1 TB
  • 2 TB
  • 3 TB
  • 4 TB
  • 5 TB
  • 6 TB
  • 8 TB
  • 10 TB
  • 12 TB
  • 14 TB

Hard Disk Partition Tables and File System

Hard Disk Drives are used to store different type of data like Operating System, Files, Folders, Executable Files, Images, Documents etc. In order to store this data, we need to use some partition table and file system which will store these data properly and in a structured manner. Following file systems can be used to use Hard Disk with different operating systems.

  • FAT is an old file system mainly used with Windows-based operating systems
  • NTFS is the newer version of the FAT file systems
  • EXT4 is a Linux based file system
  • BTRFS is a Linux based file system used enterprise servers

Hard Disk Drive Performance

In the computer, hard disk drive performance is very important. We can use different techniques to make hard disk drives more performative.

  • RAID is used with multiple disks to connect with a RAID card in different topologies.RAID will mainly read and write data into multiple disks
  • File System Defrag can be used to make the file system to put data more structured and defrag.

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