Data Storage
This article lists the various computer information systems/storage types and how they work. This article includes definitions of various types of storage, from hard drives and flash memory, such as USB drives and solid state drives (memory cards), to optical discs and smart cards. We currently use smart cards more than this article suggests.
Hard Drives
Disk Access Time
Hard drive head
Disk access time is a measurement that calculates the amount of time it takes before for a drive to read and write data. Disk access time involves three major steps: seek time, rotational delay (or rotational latency), data movement time. Seek time is the amount of time it takes for the head to move to the disk to prepare for reading. Rotational delay is the delay that occurs when waiting for the disk to begin rotating. Data movement time involves the movement of data from the disk to memory of the computer or the movement of data from the memory of the computer to the disk. Maximum rotational latency is the time it takes for the disk to perform a full rotation excluding any acceleration time. There are two types of ways in which a disk rotates: constant linear velocity and constant angular velocity. Constant linear velocity occurs when the rotational speed of the disk is dependent upon the location of the head. Constant angular velocity occurs when the disk is spun at the same speed regardless of the location of the head, like vinyl records. Certain low-noise disks utilize a slower disk access time to reduce noise created by the hard drive. Slower rotational speeds and seek speeds are purposefully installed to make sure that audible clicks and crunching sounds don't interfere with recordings.