International Business Machines Corporation

W James Kincaid

David L Levish

Jeffrey Allen Berger

Cecilia Carranza Lewis

Thomas Alexander Mahon

The present invention provides a system and method for dynamic management of buffers by the buffer manager for a hierarchical file system. A system according to the present invention includes a buffer pool which is comprised of both fixed and virtual storage. The buffer pool is logically partitioned into three states, fixed, pageable and released, wherein each of the plurality of buffers in the buffer pool exists in one of these states. The system further comprises the buffer manager, which dynamically manages the buffers in the system by moving them between these three states in a non-disruptive manner based on a comparison between the actual usage of fixed and virtual storage compared with target usage values for the fixed and virtual storage.

System and method for performing dynamic buffer management in an HFS (hierarchical file system DF/SMS)

A system and method for removing a file from a system is disclosed. The system includes a storage device and a virtual storage. The file has associated metadata that indicates a location of the file on the storage device. A first copy of the associated metadata resides on the virtual storage. A second copy of the associated metadata resides on the storage device. The system and method include marking the file as removed and updating the second copy of the associated metadata substantially immediately if the system is to run out of space on the storage device and a next scheduled update of the second copy of the associated metadata has not occurred. The system and method further include indicating that the location is available for storing data substantially immediately if the system is to run out of space on the storage device and the next scheduled update has not occurred. In one aspect, the system and method also include updating the second copy of the associated metadata during the next scheduled update if the system is not to run out of space before the next scheduled update. In this aspect, the system and method also include indicating that the location is available for storing data during the next scheduled update if the system is not to run out of space before the next scheduled update.

Method and system for performing deferred file removal in a file system

The method of the invention updates a tree arranged index for an hierarchical file system (HFS). The index includes at least one index value, i.e., an index page, that is logically positioned between an index anchor value and a sequence page. The sequence page includes actual index data. Logical positioning of the index page is determined by one or more pointers. The method initially responds to an index update request by making an update &ldquo;shadow&rdquo; copy of (i) a sequence page and (ii) any other index pages, up to and including a root page, that are to be updated in accord with the update request. Thereafter, an index manager updates the shadow copy of the sequence page in accord with the update request. The index manager further updates the root page and each shadowed index page that is present in a path to the updated sequence page to indicate that the path has been updated and includes the most current data. If a cancel or error indication occurs prior to updating of the index path, the shadowed copies of the sequence page, index page and root page are released, enabling the system to return to the non-updated pages. Otherwise, the index manager updates the index anchor value to point to the updated root page, thereby indicating that the index update has been successfully accomplished. Periodically, the new index anchor value, sequence page, index and root pages are written to disk.

Method and apparatus for shadowing a hierarchical file system index structure to enable error recovery

Disclosed is a CPU-implemented method for logically copying partitioned datasets from a source device to a target device in a storage subsystem. The method improves performance over prior logical copy utilities by substantially decreasing the number of I/O's required for the operation. A source dataset is designated on a first storage device and members are selected for copying. A target dataset is designated on a second storage device. The target dataset may be newly created or may already exist. If the latter, existing members remain alterable by other system users during copying. All selected source members, or a subset thereof, are opened for input. An equal number of target members are created in the target dataset in a single directory write operation. All data records of the selected source members are input to the CPU's virtual storage, and then transferred to the target members via frugal use of data I/O's. When the selected data records have been transferred, all target members are named using a single directory write operation. Finally, the source and target members are closed. During copying, other system users may browse the selected source members, but the unnamed target members will be invisible to them until copying is complete.

Growing community of inventors

Pebble Beach, CA, United States of America

W James Kincaid