International Business Machines Corporation

Dennis Steven DeLorme

Jeffrey John Parker

Alan Leon Levering

Richard Michael Theis

Jerry Leroy Von Berge

Michael John Oberholtzer

Margaret Rose Fenlon

Gary Ross Ricard

Larry William Youngren

Wilson D Lee

John Christopher Ripstra

Thomas Marcus McBride

George D Timms, Jr

Peter B Passe

Mark L Holm

Robert Thaddeus Gintowt

Magaret Rose Fenlon

A data structure used by an operating system to refer to a filesystem object includes information that permits the structure to be associated with filesystem objects having different filesystem implementations. The data structure is associated with a filesystem object that is linked into different directories that have different filesystem implementations. Therefore, the data structure includes respective information within it about each different link. As a result, a filesystem object, such as a directory, having one filesystem implementation may be created in or moved to another directory having a different filesystem implementation; or, a file may be linked in multiple directories having different implementations.

Method for supporting multiple filesystem implementations

A filesystem conversion process converts a filesystem from one implementation type to another type while the filesystem remains active and fully accessible. The conversion process builds a list of directories in the filesystem that are of the old filesystem type and then converts each directory until the entire filesystem is converted. Instead of the filesystem being shutdown to perform the conversion, the conversion process may run as a background thread that does not interfere with normal filesystem operations.

Method of converting a filesystem while the filesystem remains in an active state

Multiple links to the same object are managed by storing the attributes of the object in only one place. Each directory which links to the object has an object attribute table; each table has a number of entries all capable of storing the attributes of the files linked to the directory. One of the entries in a directory linked to a file stores the attributes of that file, called the master entry; other entries in the same or other directories that also link to the same file have slave entries capable of storing the attributes but not storing the attributes in their respective object attribute table. The file need only address the master entry. The master entry may point to the other slave entries which may point back to the master or to other slave entries as determined by a pointer protocol. When the master entry is to be deallocated, another of the qualified slave entries receives the attribute information and the file is updated to reflect that a new master has been declared. According to the pointer protocol, other slave entries may also be updated.

Management of multiple links to a file in a file system

A quick recovery of logical files which provide alternate views of databases is provided. Unchanged logical file pages are journaled before being changed. Transactions affecting databases covered by the logical files are also journaled. To recover a logical file, the journaled unchanged pages of the logical file that correspond to the changed pages are inserted back into the logical file, and the transactions that were journaled are processed to provide the changes to the logical file and to the database. This brings the logical file and the underlying database up to date, and in synchronization with each other.

Database index journaling for enhanced recovery

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Rochester, MN, United States of America

Dennis Steven DeLorme