1 UNESCO -NIGERIA TECHNICAL & VOCATIONAL EDUCATION REVITALISATION PROJECT -PHASE II NATIONAL DIPLOMA IN COMPUTER TECHNOLOGY File Organization and Management YEAR II- SE MESTER I THEORY Version 1: December 2008 1 2 Table of Contents WEEK 1 File Concepts .................................................................................................................................6 Bit: . .................................................................................................................................................7 Binary digit .....................................................................................................................................8 Representation ...............................................................................................................................9 Transmission ..................................................................................................................................9 Storage ............................................................................................................................................9 Storage Unit .....................................................................................................................................9 Abbreviation and symbol ............................................................................................................ 10 More than one bit ......................................................................................................................... 11 Bit, trit, dontcare, what? .............................................................................................................. 12 RfC on trivial bits ......................................................................................................................... 12 Alternative words ......................................................................................................................... 15 WEEK 2 Identifying and organizing files .................................................................................................. 16 WEEK 3 File system .................................................................................................................................... 32 Aspects of file systems ............................................................................................................... 32 File names ..................................................................................................................................... 33 Metadata ........................................................................................................................................ 33 Hierarchical file systems............................................................................................................. 34 Facilities ........................................................................................................................................ 34 Secure access .............................................................................................................................. 34 WEEK 6 Types of file systems .................................................................................................................. 35 Disk file systems .......................................................................................................................... 35 Flash file systems ........................................................................................................................ 35 Database file systems ................................................................................................................. 36 Transactional file systems .......................................................................................................... 36 Network file systems ................................................................................................................... 37 Special purpose file systems ..................................................................................................... 37 2 3 File systems and operating systems ......................................................................................... 38 Flat file systems ........................................................................................................................... 38 File systems under Unix-like operating systems ..................................................................... 39 File systems under Plan 9 from Bell Labs ................................................................................ 42 File systems under Microsoft Windows .................................................................................... 44 WEEK 7 Storing files .................................................................................................................................. 47 Backing up files ........................................................................................................................... 47 Purpose of storage ...................................................................................................................... 76 Primary storage ............................................................................................................................ 77 Secondary storage....................................................................................................................... 80 Tertiary storage ............................................................................................................................ 81 Off-line storage ............................................................................................................................ 82 Characteristics of storage .......................................................................................................... 83 Volatility ........................................................................................................................................ 84 Differentiation ............................................................................................................................... 84 Mutability ...................................................................................................................................... 84 Accessibility ................................................................................................................................. 85 Addressability .............................................................................................................................. 85 Capacity ........................................................................................................................................ 86 Performance ................................................................................................................................. 87 Fundamental storage technologies ........................................................................................... 87 Semiconductor ............................................................................................................................. 87 Magnetic ........................................................................................................................................ 88 Optical ........................................................................................................................................... 88 Paper ............................................................................................................................................. 89 Uncommon ................................................................................................................................... 89 Related technologies ................................................................................................................... 91 Network connectivity ................................................................................................................... 91 Robotic storage ............................................................................................................................ 91 File Processing ............................................................................................................................. 107 File Processing Activities ......................................................................................................... 108 3 4 Technology ............................................................................................................................................ 130 Program execution .............................................................................................................................. 130 Interrupts ................................................................................................................................................ 130 Protected mode and supervisor mode ........................................................................................... 131 Memory management ......................................................................................................................... 133 Virtual memory ..................................................................................................................................... 134 Multitasking ........................................................................................................................................... 135 Disk access