File system for a computer and method of synchronizing sets of files
AssigneeInternational Business Machines Corporation
InventorsNicholas Raymond Bailey, Christopher Derrick Cawthorne, Richard John Gadd, Robert Harris
Life of this patent
Estimating the term…
Abstract
A file system for a computer supports a plurality of directories, each maintaining a list of data files as a plurality of directory entries. As well as means for creating data entries for real data files, the system includes means for creating anti-file directory entries having an attribute indicating there is no real data file corresponding to the entry. Entries may-be moved between directories and when an anti-file and a data file of the same name are present in the same directory, the real data file is deleted. This enables the synchronization of sets of target and source files to take account of changes.
Claims20
A file system for a computer comprising non-volatile storage for storing a plurality of directories, each for maintaining at least one list of data files as a plurality of directory entries;
- first means for creating data file directory entries, each of which includes a file name, file attributes and a pointer to the location of said file data in storage;
- second means for creating anti-file directory entries, each of which includes a file name and also a file attribute indicating there is no real data file corresponding to the directory entry;
- means for moving entries between directories;
- means for comparing data file and anti-file names in said directory entries within a directory;
- and
- means responsive to an equal compare by said comparing means to delete the directory entry for the respective real data file, thereby releasing the corresponding location in storage.
A method of synchronising in a computer system a set of named target files, listed as entries in a target directory, with a set of named source files containing data, listed as entries in a source directory, the source files being subject to change in response to respective external commands to create new source data files and to delete and to modify existing source data files, the method comprising the steps of:
- in response to an external command to delete a source data file, deleting the corresponding source directory entry and creating an anti-file directory entry, being an entry with the same name but having an additional attribute indicating there is no real data file corresponding to the anti-file directory entry;
- copying all changed source data file directory entries to the target directory so as to replace any like named target directory entries with the copied directory entries;
- and
- deleting from the target directory any real data file entry having an anti-file of the same name.
A file handling computer program capable of supporting a plurality of directories, each for maintaining at least one list of data files in non-volatile storage as a plurality of directory entries;
- said computer program comprising:
- first means for creating data file directory entries, each of which includes a file name, file attributes and a pointer to the location of said file data in storage;
- second means for creating anti-file directory entries, each of which includes a file name and also a file attribute indicating there is no real data file corresponding to:the directory entry;
- means for moving entries between directories;
- means for comparing data file and anti-file names in said directory entries within a directory;
- and
- means responsive to an equal compare by said comparing means to delete the directory entry for the respective real data file, thereby releasing the corresponding location in storage.
Dependencies are inferred from the claim text.