Learn About Hard Disk Drive

A Hard disk is an Hardware drive used for permanent storage device used in a central processing unit. Hard Disk Drive or HDD consists of rotating platters of magnetic disks that store big amounts of data in a non-volatile or permanent state. That means that Hard Disk Drive or HDD data does not disappear when you turn off/restart the central processing unit or CPU.

Hard Disks are slower than main memory ( RAM ) but faster than Optical drives. HDDs usually store the operating system ( OS ) and application software of a computer.

HDD capacity is measured in gigabytes ( GB ) or billions of bytes and in terabytes ( TB ) or trillions of bytes. The performance of an HDD is determined by a variety of factors including:

Revolutions Per Minute (RPM):

 How fast the platters spin/minute. The higher this number the faster a hard disk is. At the time of writing a 7200 RPM hard disk would be the standard for desktop computers.

Cache: 

The amount of cache memory on-board the drive. The cache memory is used to store fast accessed data. It is reliable to deliver data from the cache than from the platters themselves.

Access time: 

Access time is the amount of time it takes to find and retrieve data from the hard disk. The lower the access time the faster the hard disk functions. Access time of 13-14 ms is for desktop hard drives at the time of reading/writing.