/ disk)(80 tracks/side)(18 sectors/track)(512 bytes/sector)=1,474,560 Bytes/ disk1.47 MBStore data using Longitudinal Recording or Perpendicular Recording Computing capacityMultiply number of sides, # tracks, # sectors per track, # bytes per sectorFor high density disk: 2 sides x 80 tracks x 18 sectors per track x 512 bytes per sector=1,474,560 bytes The hard disk arms move the read/write head, which reads items and writes items in the drive Location is often referred to by its cylinder Head crash occurs when read/write head touches surface of platter Always keep backup of your HD
RAID is a group of two or more integrated HD’sMain benefit is availability of storage Secondary is improved performance NASis server connected to network with sole purpose of providing storage Disk controller consists of special purpose chip and electronic circuits that control transfer of data, instructions, and info from disk to and from the system bus and other components of computer SATAEIDESCSISASHard Disks vs Disk CachePortion of RAM memory that processor uses to store frequently accessed items 1strequest for data goes to disk cache2ndrequest goes to HDMemory cards and USB Flash Drives (storage)Digital photos or files to be transportedOptical disksSoftware, movies, musicConsists of flat, round, portable disk made of metal, plastic, and lacquer that is written and read by a laserTypically store software, data, digital photos, movies, musicRead only vs rewritable How a laser reads data on optical disk:
1. Laser diode shines light beam toward a disk2. If light strikes a pit, it scatters, if light strikes a land, it reflects back toward laser diode3. Reflected light is deflected to a light sensing diode, which sends a digital signal of 1 to the computer.