Electrical computers and digital processing systems: memory – Storage accessing and control – Control technique
Reexamination Certificate
1998-07-01
2001-11-13
Yoo, Do Hyun (Department: 2186)
Electrical computers and digital processing systems: memory
Storage accessing and control
Control technique
C711S203000, C707S793000
Reexamination Certificate
active
06317814
ABSTRACT:
TECHNICAL FIELD
The present invention relates generally to multiple volume cartridge (MVC) devices, and more particularly to an arrangement for storing virtual volume data which minimizes the amount of data which could be lost due to a sudden inability to access a particular MVC.
BACKGROUND ART
Generally, automated cartridge systems (ACS) provide a mechanism by which multiple users in a data processing system can have common access to multiple data storage subsystems, such as different multiple magnetic tape cartridge devices. In such a conventional system, physical data files generated by remote user computer systems are stored individually on different tape cartridges using an addressing arrangement. With such an arrangement, the potential loss of stored data is minimized if the system suddenly loses the ability to access a given tape cartridge as a result of hardware or tape failure, i.e., only the single data file stored on the inaccessible tape is likely to be lost because that is all that is stored on any individual tape cartridge.
However, recently efficiency in mass data access and storage utilization has been improved by employing a disk buffer between the remote users and a set of multiple volume cartridges (MVC) to create virtual data volumes in place of the actual transferred data files. Efficiency and utilization are increased in such a virtual volume arrangement because multiple virtual volumes can be selectively stored on a single cartridge to maximize space utilization. Such an arrangement is described in commonly owned copending U.S. patent application Ser. No. 09/110,217, filed on Jul. 8, 1988 now patentented with U.S. Pat. No. 6,094.605 and incorporated incorporated by reference herein.
While such a multiple virtual volume arrangement significantly improves utilization and throughput efficiency, the placement of multiple virtual volumes on a single cartridge has produced an undesirable side effect by increasing the amount of data at risk to loss if a MVC hardware or cartridge failure occurs. As a result, a need exists for an improved method for storing multiple virtual volumes which minimizes the amount of data which can be potentially lost without compromising the efficiency in space utilization otherwise provided.
DISCLOSURE OF THE INVENTION
It is therefore an object of the present invention to provide an improved method for storing multiple virtual data volumes to one of a plurality of multiple volume cartridges (MVC) which minimizes the amount of data which may be lost if a particular cartridge suddenly becomes inaccessible.
It is another object of the present invention to provide a method for storing multiple virtual data volumes to one of a plurality of MVCs which allows selective copying of a virtual volume data file to more than one cartridge to minimize the amount of data which could be potentially lost if a particular cartridge suddenly becomes inaccessible.
It is still another object of the present invention to provide a method for storing multiple virtual data volumes to one of a plurality of MVCs which allows a user to selectively control copying of a virtual volume data file to different cartridges in order to minimize the amount of data which could be potentially lost if a particular cartridge suddenly becomes inaccessible.
In accordance with these and other objects, the present invention provides a method for selectively storing multiple virtual data volumes on at least one of a plurality of multiple volume cartridges (MVC) including the steps of a remote user selectively requesting at a data file level that a data volume file to be copied and stored on more than one MVC, storing all data volume files transferred from remote computer systems in a disk buffer located between the remote users and the plurality of MVCs, and automatically determining via a control subsystem whether a received data volume file has been designated for copying to at least one additional MVC. If a received data volume file has been designated for copying, the data volume stored in the disk buffer is written as a virtual data volume to more than one MVC before the data volume file is removed from the disk buffer. A record is maintained by the control subsystem indicating all MVC locations for each stored virtual volume file.
With such an arrangement, a user is advantageously permitted to selectively designate redundant back-up copying of a data volume file at the time of data transfer. If access is lost to a particular MVC, any copied data stored thereon is automatically recovered by accessing an MVC holding a copy of the data volume file. This in turn minimizes the amount of data which could be possibly lost without otherwise compromising the efficiency and flexibility provided by a multiple virtual volume data storage arrangement.
These and other objects, features, and advantages of the present invention will be readily apparent from the following detailed description of the best mode for carrying out the invention when taken in connection with the accompanying drawings.
REFERENCES:
patent: 4467421 (1984-08-01), White
patent: 5287459 (1994-02-01), Gniewek
patent: 5805864 (1998-09-01), Carlson et al.
patent: 5875478 (1999-02-01), Blumenau
patent: 5909700 (1999-06-01), Bitner et al.
patent: 5926834 (1999-07-01), Carlson et al.
patent: 5943688 (1999-08-01), Fisher et al.
patent: 6014675 (2000-01-01), Brewer et al.
Blendermann Stephen H.
Sutton Alan Ray
Brooks & Kushman P.C.
Storage Technology Corporation
Tzeng Fred F.
Yoo Do Hyun
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