Technology Systems. Level 2 BTEC Information and Creative Technology Hard Disk Drives (HDD) Level 2 BTEC Information and Creative Technology

Transcription

1 Technology Systems Hard Disk Drives (HDD)

2 Hard Disk Drive (HDD) A hard disk drive (sometimes abbreviated as Hard drive, HD, or HDD) is a device used to permanently store and also retrieve information. There are many variations, but their sizes are generally 3.5" and 2.5" for desktop and laptop computers respectively. A hard drive consists of one or more platters to which data is written using a magnetic head, all inside of an air-sealed casing. Internal hard disks reside in a drive bay, connect to the motherboard using an IDE, ATA or SATA cable, and are powered by a connection to the PSU (power supply unit).

3 HDD Sizes Hard drives come in two sizes, 3.5" and 2.5" for desktop and laptop computers respectively.

4 HDD Components

5 How is Data Read and Stored Data sent to and from the hard drive is interpreted by the disk controller, which tells the hard drive what to do and how to move the components within the drive. When the operating system needs to read or write information, it examines the hard drive's File Allocation Table (FAT) to determine file location and available write areas. Once they have been determined, the disk controller instructs the actuator to move the read/write arm and align the read/write head. Because files are often scattered throughout the platter, the head needs to move to different locations to access all information.

6 External and Internal HDD Although most hard drives are internal, there are also stand-alone devices called external hard drives, which can backup data on computers and expand the available disk space. External drives are often stored in an enclosure that helps protect the drive and allows it to interface with the computer, usually over USB, esata or the new thunderbolt connector.

7 HDD Being Replaced by SSD Solid State Drives (SSDs) have started to replace hard disk drives (HDDs) because of the distinct performance advantages they have over HDD, including faster access times and lower latency. While SSD is becoming more and more popular, HDD will continue to be in desktop computers with SSD because of the available capacity and value per dollar that HDD offers over SSD.

8 Solid State Drive (SSD) Short for Solid-State Drive or Solid-State Disk, SSD is a drive that uses nonvolatile memory as a means of storing and accessing data, much like computer RAM. Unlike hard drives, an SSD has no moving parts, which gives it advantages such as accessing stored information faster, no noise, often more reliable, and consume less power. The first SSD was implemented in IBM supercomputers in the 1970s and 1980s. They have since been drastically improved upon and offer storage capacities up to 1TB for home computers.

9 Solid State Drive (SSD)

10 Hard Drive Working in Slow Motion How a Hard Drive works in slow motion.

11 Exercise Find out and compare the speeds of the following external hard drive connection methods. USB 1, USB 2, USB 3 esata Thunderbolt.