File system - Revision history

Jnc: +Cat

2025-04-18T16:04:40Z

+Cat

Vaxorcist: /* See also */ Link to ODS-2 added

2023-03-26T07:48:26Z

‎See also: Link to ODS-2 added

Jnc: clarify

2022-04-21T05:16:27Z

clarify

Jnc: promote dirs

2022-04-20T10:06:34Z

promote dirs

Jnc: +links

2020-05-29T12:11:34Z

+links

Jnc: +cat

2018-12-16T21:22:31Z

+cat

Jnc: Link hierarchy

2018-10-31T14:52:33Z

Link hierarchy

Jnc: /* Operations provided */ one more

2017-09-24T21:11:02Z

‎Operations provided: one more

Jnc: Add typical operations provided

2017-09-23T21:56:50Z

Add typical operations provided

Jnc: Do a proper 'see also'

2017-08-07T19:45:56Z

Do a proper 'see also'

← Older revision		Revision as of 16:04, 18 April 2025
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	[[Category: OS Basics]]		[[Category: OS Basics]]
		+	[[Category: File Systems]]

@@ Line 27: / Line 27: @@
 * [[UNIX file system]]
 * [[BSD Fast File System]]
 [[Category: OS Basics]]

@@ Line 3: / Line 3: @@
 The file system takes the actual storage blocks (normally identified with a block number) on a disk, and starts by allocating enough of them to hold a [[file]] of the desired size, and then makes a record of which blocks belong to which files. It also has to know which blocks are 'free', and available for allocation - a variety of data structures are used to hold this information (free [[list]]s, free [[array]]s, etc).
-A file system also normally includes [[directory|directories]], which are collections of related files. Modern file systems are usually a tree-structured [[hierarchy]]; i.e. a directory can also include other directories, the whole being structured as a [[tree]] descending from a '''root directory'''.
+A file system also normally includes [[directory|directories]], which give the names of the files. Modern file systems are usually a tree-structured [[hierarchy]]; i.e. a directory can also include other directories, the whole being structured as a [[tree]] descending from a '''root directory'''.
 ==Operations provided==
@@ Line 21: / Line 21: @@
 Originally, the information as to which blocks were part of a file was kept in the directory; this approach was used in early operating systems such as [[Compatible Time-Sharing System|CTSS]] and [[TOPS-10]], as well as later ones like [[Multics]] and [[Windows]].
-[[UNIX]] started a new approach, in which most information about a file (particularly, which blocks were used to hold it) was kept in a separate structure (called an [[inode]] in UNIX); directories (usually implemented as an abstraction on top of the previous layer) only held mappings from file-names (visible to users) to inode numbers.
+[[UNIX]] started a new approach, in which most information about a file (particularly, which blocks were used to hold it) was kept in a separate structure (called an [[inode]] in UNIX); directories (usually implemented as an abstraction on top of the file layer) only held mappings from file-names (visible to users) to inode numbers.
 ==See also==

@@ Line 1: / Line 1: @@
 A '''file system''' is an abstraction provided by an [[operating system]] to users for them to store data aggregates of all sorts ([[program]] [[source code]], [[executable binary]], document source and formatted output, etc, etc), using names for them which make sense to the users. The actual storage itself typically uses [[secondary storage]] (generally [[disk]]).
-The file system takes the actual storage blocks (normally identified with a block number) on a disk, and starts by allocating enough of them to hold a [[file]] of the desired size, and then makes a record of which blocks belong to which files. It also has to know which blocks are 'free', and available for allocation - a variety of data structures are used to hold this information (free lists, free arrays, etc).
+The file system takes the actual storage blocks (normally identified with a block number) on a disk, and starts by allocating enough of them to hold a [[file]] of the desired size, and then makes a record of which blocks belong to which files. It also has to know which blocks are 'free', and available for allocation - a variety of data structures are used to hold this information (free [[list]]s, free [[array]]s, etc).
-A file system also normally includes '''directories''', which are collections of related files. Modern file systems are usually a tree-structured [[hierarchy]]; i.e. a directory can also include other directories, the whole being structured as a tree descending from a '''root directory'''.
+A file system also normally includes [[directory|directories]], which are collections of related files. Modern file systems are usually a tree-structured [[hierarchy]]; i.e. a directory can also include other directories, the whole being structured as a [[tree]] descending from a '''root directory'''.
 ==Operations provided==
@@ Line 19: / Line 19: @@
 Two main approaches have been used to organize file systems internally.
-Originally, the information as to which blocks were part of a file was kept in the directory, along with other meta-information about the file (date last modified, etc); this approach was used in early operating systems such as [[Multics]], as well as later ones like [[Windows]].
+Originally, the information as to which blocks were part of a file was kept in the directory; this approach was used in early operating systems such as [[Compatible Time-Sharing System|CTSS]] and [[TOPS-10]], as well as later ones like [[Multics]] and [[Windows]].
 [[UNIX]] started a new approach, in which most information about a file (particularly, which blocks were used to hold it) was kept in a separate structure (called an [[inode]] in UNIX); directories (usually implemented as an abstraction on top of the previous layer) only held mappings from file-names (visible to users) to inode numbers.

← Older revision		Revision as of 12:11, 29 May 2020
Line 1:		Line 1:
−	A '''file system''' is an abstraction provided by an [[operating system]] to users for them to store data aggregates of all sorts (program source, [[executable binary]], document source and formatted output, etc, etc), using names for them which make sense to the users. The actual storage itself typically uses [[secondary storage]] (generally [[disk]]).	+	A '''file system''' is an abstraction provided by an [[operating system]] to users for them to store data aggregates of all sorts ([[program]] [[source code]], [[executable binary]], document source and formatted output, etc, etc), using names for them which make sense to the users. The actual storage itself typically uses [[secondary storage]] (generally [[disk]]).

	The file system takes the actual storage blocks (normally identified with a block number) on a disk, and starts by allocating enough of them to hold a [[file]] of the desired size, and then makes a record of which blocks belong to which files. It also has to know which blocks are 'free', and available for allocation - a variety of data structures are used to hold this information (free lists, free arrays, etc).		The file system takes the actual storage blocks (normally identified with a block number) on a disk, and starts by allocating enough of them to hold a [[file]] of the desired size, and then makes a record of which blocks belong to which files. It also has to know which blocks are 'free', and available for allocation - a variety of data structures are used to hold this information (free lists, free arrays, etc).

← Older revision		Revision as of 21:22, 16 December 2018
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	* [[UNIX file system]]		* [[UNIX file system]]
	* [[BSD Fast File System]]		* [[BSD Fast File System]]
		+
		+	[[Category: OS Basics]]

@@ Line 12: / Line 12: @@
 * reading and writing them;
 * moving to a different position in a file prior to reading/writing;
-* creating new files, and deleting existing ones.
+* creating new files, and deleting existing ones;
 ==Approaches==

← Older revision		Revision as of 19:45, 7 August 2017
Line 11:		Line 11:
	Originally, the information as to which blocks were part of a file was kept in the directory, along with other meta-information about the file (date last modified, etc); this approach was used in early operating systems such as [[Multics]], as well as later ones like [[Windows]].		Originally, the information as to which blocks were part of a file was kept in the directory, along with other meta-information about the file (date last modified, etc); this approach was used in early operating systems such as [[Multics]], as well as later ones like [[Windows]].

−	[[UNIX]] started a new approach, in which most information about a file (particularly, which blocks were used to hold it) was kept in a separate structure (called an [[inode]] in UNIX); directories (usually implemented as an abstraction on top of the previous layer) only held mappings from file-names (visible to users) to inode numbers. ~~(More information about UNIX file-systems can be found~~ [[UNIX file system~~\|here~~]].)	+	[[UNIX]] started a new approach, in which most information about a file (particularly, which blocks were used to hold it) was kept in a separate structure (called an [[inode]] in UNIX); directories (usually implemented as an abstraction on top of the previous layer) only held mappings from file-names (visible to users) to inode numbers.
		+
		+	==See also==
		+
		+	* [[UNIX file system]]
		+	* [[BSD Fast File System]]