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`Computer Technology
`Encyclopedia: Quick
`Reference for Students
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`and Professionals
`
`Michael Graves
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`:5 DELMAR
`II: CENGAGE Learning"
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`Austra Ia
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`~.,’ DELMAR
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`Computer Technology Encyclopedia: Quick
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`Michael Graves
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`file system I 183
`
`A typical file system is hierarchical, meaning it defines the location of data in
`layers. In a hierarchical system, a hard disk can be divided into partitions, which
`subsequently can be broken up into directories. Multiple subdirectories reside beneath
`the primary directories and files can reside beneath any directory or subdirectory. The
`file system keeps entries for every piece of data stored on the system that includes a
`lot of information about each file. Such information includes the location of data as
`
`described, but it also can include information such as file attributes and permissions.
`Some file systems allow data to be compressed and decompressed on the fly and
`some allow data to be encrypted and decrypted on the fly.
`File systems can be journaling or versioning in nature. A journaling file
`system gets its name because it keeps a journal of all files. Before a change to any
`given file is written to the system, the journal entry for that file is updated with
`critical changes, such as file size, sector locations, and so forth. A versioning file
`system allows a file to exist in multiple incarnations. When changes are made to
`the file and then saved, the original file is renamed and stored intact. This way
`if the user decides that the changes weren’t for the better, she can go back to an
`earlier version. Most versioning file systems allow the user to configure how many
`versions to keep before overwriting the oldest version. Table E4 lists a number of
`commonly seen file systems with a brief description of each.
`
`TABLE FA
`
`File naming convention specifications
`
`FILE SYSTEM
`
`
`FILE NAME LENGTH
`DATABASE
`
`
`
`File allocation tables
`
`
`
`File allocation tables
`Microsott
`
`
`
`
`File allocation tables
`
`NTFS
`Microsoft
`Master tile table
`
`
`
`HPFS
`IBMi
`
`
`Apple
`Unicode database
`
`
`
`ISO 9660
`Descriptor database
`
`
`
`Universal
`UDF Plain
`Block mapping
`
`
`Universal
`UDF VAT
`Block mapping
`
`
`
`UDF
`Universal
`255
`
`
`Spared
`
`
`‘ File name was limited to eleven characters, but a maximum of eight could be used tor the tile name, with three characters
`reserved For the extension.
`
`
`
`Metatile database
`
`Block mapping with
`sparing table
`
`HFS
`
`
`
`
`
`
`
`lThere were 255 characters included the tile extension, which can be any length.
`l Jointly developed between Microsoft and IBM, but IBM retained ownership alter the partnership was dissolved. Early Microsott
`products included some support For HTFS.
`§ISO 9660 defines three levels at tile name. A Level 1 File name emulates the MS-DOS 8.3 File name. A Level 2 tile name loosely
`emulates the long tile names supported by FAT32 and NTFS, but must include a l-byte counter along with File name byte
`counter. This typically limits ISO 9660 Files to I55 to T60 characters.
`
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