Computers: Information Technology in Perspective By Long and Long Copyright 2002 Prentice Hall, Inc. Storing & Retrieving Information File systems J. Holvikivi 2012

Quit 4.2 Mass Storage and Files  Programs and information (text, numbers, image, audio, video) are stored: Temporarily in RAM Temporarily in RAM Permanently in Mass Storage (disks, flash memory and cloud) Permanently in Mass Storage (disks, flash memory and cloud)

Quit Computer Files  ASCII file (txt), Unicode  Data file  Document file: doc, docx, odt, pdf, xps  Spreadsheet file  Source program file.js  Executable program file.exe  Graphics file  Audio file mp3  Video file.txt.mdb.vdp.xls.html.gif.bmp.jpg.exe.tif.wav.mov

Quit File Name Conventions 2001 Resume.doc separated by a period file extension (1 - 4 characters, optional) filename (up to 255 chars)

Quit E: CD/DVD drive A: Floppy drive (history) T: network drive System Unit Drive Designator Possibilities C: Hard drive Courtesy of Imation Corporation F: USB memory

Quit Physical Storage Process Storage medium Storage device –Sequential and/or Random –Write/Save –Read/Open –Encryption –Sequential and/or Random –Write/Save –Read/Open –Encryption Storage process

Quit Offline and Online Magnetic Disks Magnetic Disk Hard/Fixed Disks Online only Mechanical device Interchangeable Disks

Quit 4.8 Hard Disks  Fast and lots of storage  >400 GB permanently installed  - 1 TB external  Anatomy: Recording surface Recording surface Multiple platters Multiple platters Read/write head Read/write head Access arms Access arms Courtesy of Seagate Technology

Quit 4.9 Fixed Hard Disk

Quit Magnetic Disk Organization  Disk Address Tracks/Sectors/Clusters Tracks/Sectors/Clusters Cylinders Cylinders  Write data Magnetize disk’s thin coated surface Magnetize disk’s thin coated surface  Read data Sense absence or presence of a bit Sense absence or presence of a bit

Quit 4.11 Magnetic Disk Organization  VFAT: Virtual File Allocation Table  CheckDisk for repairs  Defragmentation  Formatting  Disk Speed Access time Access time Data transfer rate Data transfer rate Disk caching Disk caching

Quit 4.12 Memory device Care  Do store in protected spot, away from sun and magnets, phones  Do remove before turning off computer  Mark clearly and add a string!  Don’t expose to extreme temperatures  Don’t touch surface (CD)  Don’t remove if drive light is on  Don’t force it in/out of the drive

Quit 4.13 Computer Viruses  Via Internet when downloading files, video, Flash and pdf  Via as attachments or links  Via USB memory  Via computer networks and peer to peer networks  Also in mobile devices  Use anti-viral and network security program and UPDATE it automatically!

Quit 4.14 Backing Up Files  Back-ups used for: Backup or protection Backup or protection Archiving Archiving  Tape backup units (TBUs)  CD-RW, DVD, Blu-ray  External hard disk  Flash memory, SSD (SSD solid state drive)  On networks: servers or cloud  Back-ups used for: Backup or protection Backup or protection Archiving Archiving  Tape backup units (TBUs)  CD-RW, DVD, Blu-ray  External hard disk  Flash memory, SSD (SSD solid state drive)  On networks: servers or cloud

Quit 4.15 Backing Up Files  Backup methods: Full Full Selective Selective Modified files only Modified files only  Internet and network servers Must be made fault-tolerant Must be made fault-tolerant Use RAID (Redundant Array of Independent Disks) for backup Use RAID (Redundant Array of Independent Disks) for backup NAS network access server NAS network access server

Quit 4.16 Speed Comparison processorRAMbusprocessorRAMbus Hard disk USB flash memory Blu-ray, DVD, CD USB flash memory Blu-ray, DVD, CD

Computers: Information Technology in Perspective By Long and Long Copyright 2002 Prentice Hall, Inc. Storing & Retrieving Information The End