Electrical computers and digital processing systems: memory – Storage accessing and control – Control technique
Reexamination Certificate
1998-04-01
2001-08-07
Yoo, Do Hyun (Department: 2185)
Electrical computers and digital processing systems: memory
Storage accessing and control
Control technique
C711S111000
Reexamination Certificate
active
06272606
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to methods and apparatus for automated job scheduling in a data storage and/or retrieval system.
2. Description of the Prior Art
Centralised computer data storage and/or retrieval systems have been proposed in which the data storage and/or retrieval system is shared between many “client” computers—i.e. computers individually requiring to store or retrieve a quantity of data.
An example of such a system is a video archiving system for professional use—e.g. by a television broadcasting station. Here, a central archive of very many hours of video material might be stored on digital video tapes. Since the amount of archived material to be stored is likely to be very much more than can be fitted onto one tape, it has been proposed that an automated tape handling mechanism such as a robotic tape changer could be used. A robotic tape changer of this type is typically able to unload a tape cassette from a tape recording/replay machine (e.g. a video tape recorder or VTR), to return the tape cassette to the correct place in a tape cassette shelving or racking system, to pick up the next tape cassette from the racking system and to load it into the VTR.
However, these operations all take time. There is a certain amount of time associated with the actions of the robotic changing mechanism, and also a significant (and often much greater) amount of time needed to rewind and unload a current tape cassette, and then to load and cue up a next tape cassette. These time penalties would be present simply because a storage medium based on multiple storage volumes (tape cassettes) is in use; the robotic arrangement simply adds to the already-existing problem.
So, there is a need to reduce, wherever possible, the time taking in accessing data held on a multi-volume storage medium.
SUMMARY OF THE INVENTION
This invention provides a method of scheduling data storage or retrieval jobs in a data storage and/or retrieval system in which stored data is distributed between multiple data storage volumes, the method comprising:
(i) maintaining a queue of data storage or retrieval jobs for execution; and
(ii) adding a newly initiated job to the queue so that:
(a) if the newly initiated job requires access to the same data storage volume as a further job already in the queue, the newly initiated job is added to the queue at an adjacent queue position to that further job; and
(b) if the newly initiated job does not require access to the same data storage volume as any other job already in the queue, adding the newly initiated job to the queue at a queue position independent of the data storage volumes of other jobs in the queue.
In this way, the invention can optimise or at least improve the way in which data storage and retrieval jobs are added to a job queue, by ensuring that where possible a newly added job is added to the queue at a queue position adjacent to a job requiring access to the same data storage volume. This can avoid the need to unload and reload a data storage volume between execution of the two jobs, so saving the time associated with those operations.
REFERENCES:
patent: 4636946 (1987-01-01), Hartung et al.
patent: 4876662 (1989-10-01), Pence
patent: 4974197 (1990-11-01), Blount et al.
patent: 5235572 (1993-08-01), Tamai
patent: 5469560 (1995-11-01), Beglin
patent: 5500803 (1996-03-01), Munro et al.
patent: 5664143 (1997-09-01), Olbrich
patent: 5890208 (1999-03-01), Kwon
patent: 0 482 802 (1992-04-01), None
patent: 0 508 666 (1992-10-01), None
Yu et al. Query Pre-Execution and Batching in Paradise. Technical Report, University of Wisconsin, Madison, Mar. 1996.*
Yu et al. Query Pre-Execution and Batching in Paradise. Scientific and Statistical Database Management, 1997;64-78.
Chandler Simon
Dorricott Martin Rex
Encarnacion Yamir
Frommer William S.
Frommer Lawrence & Haug LLP.
Savit Glenn F.
Sony United Kingdom Limited
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