International Business Machines Corporation

James Lawrence Tilbury

Leon Edward Gregg

Armin Harold Christofferson

Thomas Alan Bjork

James Michael Van Oosbree

Andrew Thomas Tauferner

Daniel Joseph Strauss

Ellen M Stacey

Matthew S Johnston

Richard L Tilbury

A space allocator in a file management system maintains and uses one or more offsets and a stored value of the largest space skipped on previous scans to increase the efficiency of scans for available space in a file system space map. When the space allocator determines a current allocation request is greater than the largest space skipped in the previous scan, a last allocated offset can be used to begin scanning to reduce the portion of the map to scan in order to find available space. When the space allocator determines the current allocation request is less than or equal to the largest space skipped in the previous scan, a first available offset can be used to begin scanning for an appropriate unused space.

Efficient detection of available space in a file system space map

A method, apparatus and program product utilize a flight recorder having active error detection functionality to proactively detect errors in a computer or a sub-system or component thereof. The active error detection may be based on one or more trends detected in the trace data logged by the flight recorder and reflective of particular types of errors that may be present in a computer during operation, such that an error may be logged, and in some instances, an exception may be triggered.

Computer flight recorder with active error detection

The present invention provides an apparatus, method, and computer program product for sharing resources within a robotic media library having multiple media types and multiple device types amongst a plurality of connected servers.

Sharing resources within a robotic media library amongst a plurality of connected servers

A method is provided for restricted update sharing of removable media in a media library. Media is allowed to be retrieved from storage slots of a media library and moved to a drive in a restricted update mode. The media includes short term attributes that include short term media data structures, and long term attributes. A file system includes short term memory and long term memory associated with the media. Updates to the long term attributes and long term memory are restricted. Updates to the short term attributes and the short term memory are allowed. The short term memory of the file system is refreshed each time the media is moved to the drive, which includes changing data in the short term memory back to an original state and rebuilding the data in the short term memory from the media data structures of the short term attributes.

Methods for restricted update sharing of removable media in a media library

A method, apparatus and computer program product are provided for implementing autonomous variation of media dismount time in a robotic media library. I/O requests to the robotic media library are monitored. Performance statistics are gathered for the I/O requests to the robotic media library. The gathered performance statistics are periodically checked to determine if a change is needed for the media dismount time. The gathered performance statistics include a media hit count of where a data storage medium (DSM) for an I/O request is in a robotic media drive, and a media near miss count where the DSM for the I/O request is in transit from the robotic media drive.

Method and apparatus for implementing autonomous variation of media dismount time in a robotic media library

An apparatus, program product and method utilize a cache payback parameter for selectively and dynamically disabling caching for potentially cacheable operations performed in connection with a memory. The cache payback parameter is tracked concurrently with the performance of a plurality of cacheable operations on a memory, and is used to determine the effectiveness, or potential payback, of caching in a particular implementation or environment. The selective disabling of caching, in turn, is applied at least to future cacheable operations based upon a determination that the cache payback parameter meets a caching disable threshold.

Dynamic cache disable

A method, apparatus and article of manufacture for allocating use of an access device between a host operating system and a guest operating system. In one embodiment, a source of the received request to use the access device is determined as either the host operating system or the guest operating system. A determination of whether the host or guest operating system has a key for the access device is performed. The key enables either the host operating system or the guest operating system to use the access device. A determination of whether the received request is an altering request to change a state of the access device or a passive request to read the access device is also performed. The processing of the request from the host and guest operating systems is similar except when the request is an altering request and neither the host operating system nor the guest operating system has the key. In this case, the request from the host operating system is passed and the request from the guest operating system is rejected.

Method and apparatus for allocating use of an access device between host and guest operating systems

The present invention provides methods and systems for creating and manipulating universal disk format (UDF) data structures having variable amounts of data. For some embodiments, a UDF data structure is formatted with a freespace bitmap field large enough to represent a first amount of data and an area adjacent the freespace bitmap field reserved to allow the freespace bitmap field to expand to represent a second amount of data greater than the first amount of data. The freespace bitmap field may be expanded to represent the second amount of data by increasing a freespace bitmap size field to represent an expanded freespace bitmap field and initializing the expanded portion of the freespace bitmap size field.

Universal disk format volumes with variable size

Disclosed is a system, method, and program for processing an input file in a file system, wherein the input file has an input file name. A function is applied to map the input file name to a value. A data structure is processed to determine whether there is a preexisting file in the file system having a name that maps, according to the function, to the same value to which the input file name maps. Two files that map to a same value according to the function are capable of having a same name.

Method, system, and program for accessing files in a file system

A method, apparatus and article of manufacture for copying information from a first storage medium to a second storage medium. A first storage medium of memory blocks is mapped into at least one data block and at least one directory block. Two passes of the first storage medium are then performed. In the first pass, each data block is copied from the first storage medium to the second storage medium. If a read error occurs while copying a data block, a location of the data block and a data file stored in the data block are identified to provide future error handling capability. In the second pass, each directory block is copied from the first storage medium to the second storage medium.

Growing community of inventors

Rochester, MN, United States of America

James Lawrence Tilbury