CHAPTER 6 66 Secondary Storage

6 © The McGraw-Hill Companies, Inc Objectives 1.Floppy and hard disks 2.Cartridges and disk packs 3.Performance enhancements 4.Compact disks 5.Specialized disks

6 © The McGraw-Hill Companies, Inc Secondary Storage Save information Permanent storage Temporary storage

6 © The McGraw-Hill Companies, Inc Floppy Disks Removable Write-protect Parts –Tracks –Sectors

6 © The McGraw-Hill Companies, Inc New Standards Zip Disks –250 MB SuperDisks –120 MB HiFD disks –200 MB

6 © The McGraw-Hill Companies, Inc Hard Disks Metallic disks Fast information Read-write heads Three types –internal hard disk –hard-disk cartridge –hard-disk pack

6 © The McGraw-Hill Companies, Inc Human hair dust particle fingerprint smoke particle disk head disk surface

6 © The McGraw-Hill Companies, Inc Internal Hard Disk Inside system unit Advantage over floppy disks Capacity: 80 gig

6 © The McGraw-Hill Companies, Inc Hard-disk Cartridges Easy removal Complements internal –JAZ from Iomega –SPARQ from SyQuest

6 © The McGraw-Hill Companies, Inc Hard-disk Packs Removable Massive storage capacity Common in mainframes Resembles stack of vinyl records

6 © The McGraw-Hill Companies, Inc Performance Enhancements Disk caching Redundant arrays of inexpensive disks (RAID) File compression and decompression

6 © The McGraw-Hill Companies, Inc Compact Permanent storage Laser beams reflect off pits Three types Optical Disks

6 © The McGraw-Hill Companies, Inc CD-ROM Compact disc-read- only memory Not written to 650 MB capacity

6 © The McGraw-Hill Companies, Inc CD-R & CD-RW CD-Recordable or WORM CD-RW or rewritable optical discs

6 © The McGraw-Hill Companies, Inc CD-R for Music Download from Internet Arrange and play music Create custom CD-R or CD-RW

6 © The McGraw-Hill Companies, Inc DVD Digital Versatile Disk or Digital Video Disk Types –DVD-ROM –DVD-R –DVD-RAM or DVD-RW

6 © The McGraw-Hill Companies, Inc Magnetic Tape Fast, direct access Sequential access Storage and backup

6 © The McGraw-Hill Companies, Inc Streamers Backup tape for microcomputer Capacities range from 120 MB to 5 GB Digital audio tape (DAT)

6 © The McGraw-Hill Companies, Inc Reels Minicomputer and mainframe 1/2 inch wide and 1/2 mile long Stores 1600 to 6400 cpi* Run on magnetic tape drives or magnetic tape units

6 © The McGraw-Hill Companies, Inc A Look to the Future Near-field recording devices Holographic storage systems

6 © The McGraw-Hill Companies, Inc. 2002