COMSCI 2101 - Device Management Part 2

Direct Access Storage Devices (DASD)

devices that can directly read or write to a specific place

Magnetic Disks (Fixed-Head, Movable-Head)
Optical Discs
Flash Memory

DASD is grouped into 3 categories:

Fixed-Head Magnetic Disk Storage

looks like cd or dvd covered with magnetic film that has been formatted

Track

each circle in fixed-head magnetic disk storage is called?

Fixed-Headd Magnetic Disk Storage

Data is recorded serially on each track by the fixed read/write head position over it.

Movable-Head Magnetic Disk Storage

Like a computer hard drives that have one read/write head that floats over each surface of each disk. The number of tracks typically a thousand or more.

Movable-Head Magnetic Disk Storage

The disk can be a single platter or part of a disk pack/stack of magnetic platters.

Optical Disc Storage

Was made possible by developments in laser technology. Single spiraling track of same-sized sectors. Running from the center to the rim of the disc.

Optical Disc Storage

consists of a single spiraling track of same-sized sectors running from the center to the rim of the disc.

Pits

a high-intensity laser beam burns indentations on the disc that are?

Lands

contrast with the unburned flat areas, and represent 1s

Constant Angular Velocity (CAV)

A magnetic disk, which consists of concentric tracks of sectors, spins at a constant speed.

Constant Linear Velocity (CLV)

The disc drive adjusts the speed of the disc's spin to compensate for the sector's location on the disc.

Flash Memory Storage

a type of electrically erasable programmable read-only memory (EEPROM). nonvolatile removable medium that emulates random access memory, but, unlike RAM, stores data securely even when it's removed from its power source.

Flash Memory Storage

used to store startup (boot up) information for computers

10,000 to 1,000,000 uses

how many number of uses before a flash memory device will no longer reliably store data?