Hard drives

A Hard disk drive is a storage device where data is written and read in any order. HDD's are non-volatile meaning they retain data even when the power is off. Modern HDD's come in 2 different form factors 3.5 inch and 2.5 inch. They are connected to the system via SATA (Serial ATA), SAS (Serial Attached SCSI) and USB cables. Hard disk drives are made up of a spindle  which spins a flat circular disk called a platter, this is where data is read and written, A actuator arm which controls the read/write head. HDD's platters these days spin at a variety of speeds usually between 5,400 rpm to 7,200 rpm. Higher end HDD's can spin to 15,000 rpm. There are 2 ways HDD's are connected,

  • Internal HDD's - which are connected internally usually through a SATA cable
  • External HDD's - which are placed externally connected through a USB or Firewire cable

There are 2 types of Hard disk drives. Mechanical HDD's usually 3.5 inches which use magnetic storage and Solid-State Drives (SSD). Solid-State Drives are 2.5 inches don't have any mechanical parts and use flash memory. SSD's have higher data transfer rates, use less power and are more reliable. Solid-State Drives have lower latency and access times.

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