International Business Machines Corporation

Lenovo (singapore) Pte. Ltd.

Robert F Buxton

Stephen James Hobson

Paul Kettley

Peter Siddall

Robert Daniel Millar

Paul Hopewell

Stephen Richard Walker

Jose Emir Garza

Andrew Ian Hickson

John Simon Tilling

David James Fisher

Richard M W Harran

Dennis Jack Zimmer

Peter James Lupton

Ian Hunter

Handel Glasnant Price

Adam Richards

Ian W Parkson

An apparatus browses a list of data items. The apparatus includes a plurality of browse mechanisms each operable to scan concurrently through a list of data items and a plurality of independent groups each comprising two or more of the plurality of browse mechanisms. The browse mechanisms in a group cooperate together to browse the list of data items such that a data item is seen by only one member of the group.

Browsing a list of data items

Provided are methods, data processing systems, recovery components and computer programs for recovering from storage failures affecting data repositories. At least a part of the recovery processing is performed while the data repositories are able to receive new data and to allow retrieval of such new data. Although new data items may be received into the repository and retrieved therefrom during recovery processing, updates to the data repository which were performed before the failure and which are then restored to the repository by the recovery processing are restored within a recovery unit of work and are inaccessible to processes other than the recovery process until successful completion of the recovery unit of work. The recovery processing ensures that the recovered repository is consistent with the state of the repository at the time of the failure, but is available for addition and retrieval of new data items before completion of the recovery processing.

Recovery from failures within data processing systems

The invention relates to the recovery of data in a database of database records, following a failure of a media containing said database. The data recovery uses a backup of the database and a log of log records detailing any changes in the database which are not captured in the backup. The log is replayed starting with the most recent log record. It is the determined for each successive log record, that relates to an operation on a database record, whether processing the log record will result in the most recent state of the corresponding database record, and if so, the log record is processed. Subsequently additional data is restored from the backup.

Data recovery system

A method of moving records, stored on a recovery log, which are associated with units of work which have waited for a long time is described. Units of work which have waited for a long time, such as those which are in-doubt have their records copied from a recovery log to a secondary log. When the earliest-written record for this in-doubt unit of work has been copied, a new record called a fork record is written on to the recovery log which has two effects: to subtract the log records currently on the recovery log for this unit of work from the recovery log and to refer to the copied records written on the secondary log. The new record achieves this using two pointers, a pointer to point to the most-recently written record on the recovery log for this unit of work and a pointer to point to the most-recently written record on the secondary log for this unit of work.

Management of units of work on a computer system log

Growing community of inventors

Chandlers Ford, United Kingdom

Robert F Buxton