US 5,313,646 AGranted

Method and apparatus for translucent file system

AssigneeSun Microsystems, Inc.

InventorsDavid Hendricks, Evan Adams, Tom Lyon, Terrence C. Miller

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Abstract

In a computer system having a hierarchical file structure, a file system is provided which permits users of the system to share a file hierarchy and also have a private hierarchy in which files are automatically copied to as they are modified. Through the system of the present invention, a directory appears to the user as a single directory but may actually comprise files originating from a number of directories which are connected to one another through search links. Each directory has a search link associated with it which contains the path name of the back layer or directory behind it. The first layer seen through the system of the present invention is the front layer, private to the user. The back layers behind the front layer and connected to the front layer through the search links are shared layers accessible to multiple users. Thus transparent to the user of the directory accessible comprises multiple layers comprising shared and private files. The system further provides a copy-on-write feature which protects the integrity of the shared files by automatically copying a shared file into the users private layer when the user attempts to modify a shared file in a back layer.

Claims16

Dependent claims

In a multi-user computer system comprising a central processing unit (CPU), an input/output unit and memory, said CPU being controlled by an operating system, said operating system comprising a file system module, wherein the file system module organizes and controls access to files located on disks in the computer system, said file system module organizing files into file systems comprising directories said directories containing files organized in a hierarchical file structure, a method for translucently providing to a user both shared and private access to current revisions of files, said method comprising the steps of:

structuring a designated file hierarchy into two or more layers whereby each layer contains at least one directory;
creating an ordered set of layers which can be shared by any number of users, wherein two or more layers of the designated file hierarchy are arranged in time-of-creation sequence such that a layer containing a less recent revision of a file in the designated file hierarchy is placed below a layer with a more recent revision of the same file;
providing one or more front layers, each containing at least one directory, with each of the one or more front layers being controlled by a particular user of the system and is not being shared with other users of the system, with files located in each of said one or more front layers being designated such that only the particular user can read from and write to the files in said particular user's front layer, and each front layer being positioned in front of the ordered set of shared layers of the designated file hierarchy;
displaying to a particular user, most recent revisions of files regardless of whether these files reside in the directory of the particular user's front layer or in the directories of the ordered set of shared layers, as if all of the files resided in the particular user's front directory.

1 more element

In a multi-user computer system comprising a central processing unit (CPU), an input/output unit and memory, said CPU being controlled by an operating system, said operating system comprising a file system module, wherein the file system module organizes and controls access to files located on disks in the computer system, said file system module organizing files into file systems comprising directories and files organized in a hierarchical file structure, said directories containing the files, a translucent file system module which cooperates with the file system module, said translucent file system module comprising:

organizing means for structuring a designated file hierarchy into two or more layers whereby each layer contains at least one directory;
ordering means for creating an ordered set of layers which can be shared by any number of users, wherein the two or more layers of the designated file hierarchy are arranged in time-of-creation sequence such that a layer containing a less recent revision of a file in the designated file hierarchy is placed below a layer with a more recent revision of the same file;
a first layering means for providing one or more front layers, each containing at least one directory, with each of the one or more front layers being controlled by a particular user of the system and not being shared with other users of the system, with files located in each of said one or more front layers being designated such that only the particular user can read from and write to the files in the particular user's front layer and each particular user's front layer being positioned in front of the ordered set of shared layers of the designated file hierarchy;
and
display means for displaying to a particular user, most recent revisions of files regardless of whether these files reside in the directory of the particular user's front layer or in the directories of the ordered set of shared layers, as if all of the files resided in the particular user's front directory.

2 more elements

Dependencies are inferred from the claim text.

Facts

Application: 07/714,312Filed 10 Jun 1991 · continuation
Priority: 10 Jun 1989
Granted: 17 May 1994
Term ends: Not estimatedThe source records don’t support an estimate.

Classification5 codes

G06F 16/902
Using directory or table look-up: using more than one table in sequence, i.e. systems with three or more layers
G06F 16/192
Virtual file systems: implementing virtual folder structures
Y10S 707/99942
Database schema or data structure: manipulating data structure, e.g. compression, compaction, compilation
G06F
Computing and data processing