Donald M Nordahl

US Patent:

7171514, Jan 30, 2007

Filed:

Nov 20, 2003

Appl. No.:

10/719486

Inventors:

Juan A. Coronado - Tucson AZ, US
Matthew J. Kalos - Tucson AZ, US
Donald M. Nordahl - Tucson AZ, US
Richard A. Ripberger - Tucson AZ, US

Assignee:

International Business Machines Corporation - Armonk NY

International Classification:

G06F 12/00

US Classification:

711112

Abstract:

A method to control access to logical volumes disposed in an information storage and retrieval system using parallel access volumes. The method provides an information storage and retrieval system comprising a plurality of logical volumes, and a plurality of host computers, where each host computers is capable of communicating with the information storage and retrieval system. The method creates a parallel access volume having an alias, and persistently associates that parallel access volume with an original base logical volume, where the original base logical volume may be assigned to one of (N) logical volume groups. If the original base logical volume is assigned to the (i)th logical volume group, the method permits each host computers assigned to the (i)th host computer group to access the original base logical volume, or the current base logical volume, associated with the parallel access volume.

US Patent:

7512735, Mar 31, 2009

Filed:

Nov 20, 2003

Appl. No.:

10/719488

Inventors:

Ezequiel Cervantes - Tucson AZ, US
Juan A. Coronado - Tucson AZ, US
Miguel A. Duanas - Tucson AZ, US
David P. Goodman - Loveland CO, US
Matthew J. Kalos - Tucson AZ, US
Donald M. Nordahl - Tucson AZ, US
Richard A. Ripberger - Tucson AZ, US

Assignee:

International Business Machines Corporation - Armonk NY

International Classification:

G06F 12/00

US Classification:

711113

Abstract:

A method to control access to logical volumes. The method provides a plurality of host computers and an information storage and retrieval system comprising a plurality of logical volumes. The method forms (N) host computer groups, assigns one or more of the host computers to the (i)th host computer group, such that each host computer assigned to (i)th host computer group is not assigned to any other of the (N) host computer groups. The method forms (N) logical volume groups, assigns one or more logical volumes to the (i)th logical volume group, such that each of the logical volumes assigned to the (i)th logical volume group is not assigned to any other of the (N) logical volume groups. The method maintains a database associating the (i)th host computer group with the (i)th logical volume group, and permits a host computer assigned to the (i)th host computer group to access a logical volume assigned to the (i)th logical volume group.

US Patent:

20050114465, May 26, 2005

Filed:

Nov 20, 2003

Appl. No.:

10/719487

Inventors:

Juan Coronado - Tucson AZ, US
Matthew Kalos - Tucson AZ, US
Donald Nordahl - Tucson AZ, US
Richard Ripberger - Tucson AZ, US

International Classification:

G06F015/167
G06F015/177

US Classification:

709214000, 709220000

Abstract:

A method to control access to logical volumes disposed in one or more information storage and retrieval systems when using copy service relationships. The method provides a first information storage and retrieval system, a second information storage and retrieval system, and a plurality of host computers capable of communicating with the first information storage and retrieval system. The method forms (N) host computer group, and assigns each of the plurality of host computers to the a host computer group. The method forms (N) logical volume groups, and assigns one or more of the plurality of first logical volumes to a logical volume group. The method receives a request from a host computer assigned to the (i)th host computer group to establish a copy service relationship between a source logical volume and a target logical volume. The method determines if both the source and target logical volumes are assigned to the (i)th logical volume group. If both the source and target logical volumes are assigned to the (i)th logical volume group, then the method establishes the requested copy service relationship.

US Patent:

54267587, Jun 20, 1995

Filed:

Sep 23, 1992

Appl. No.:

7/949672

Inventors:

Susan K. Candelaria - Tucson AZ
Dean L. Hanson - Tucson AZ
Robert L. Kwok - San Jose CA
Kenneth W. Lane - Tucson AZ
Donald M. Nordahl - Tucson AZ
Mark A. Reid - Tucson AZ
William G. Sherman - Tucson AZ

Assignee:

International Business Machines Corporation - Armonk NY

International Classification:

G06F 1200
G11B 555

US Classification:

395425

Abstract:

A method and system for enhancing the efficiency of data accessing within a storage subsystem which is coupled to a host system via a storage subsystem controller and a data channel. The storage subsystem controller preferably includes a tracked cyclic storage device which has multiple disks which are rotatable about a single spindle. Recording tracks within each disk are then accessed utilizing multiple switchable transducer heads. A signal transmitted from the host system is utilized to define a sequence in which a group of recording tracks are to be accessed. That signal is then utilized to create a transducer head switching table within the storage subsystem controller which lists each recording track to be accessed and an associated control parameter for selecting a particular transducer head to be utilized to access a subsequent recording track. Each time the end of an accessed recording track is encountered, the transducer head switching table is accessed and the control parameter associated with that track is accessed and coupled to the tracked cyclic storage device transducer head switch in order to select a subsequent recording track for access. In this manner, a plurality of tracks may be accessed in any desired order.

US Patent:

52356922, Aug 10, 1993

Filed:

Aug 31, 1990

Appl. No.:

7/576044

Inventors:

Kathryn J. Ayres - Tucson AZ
Brent C. Beardsley - Tucson AZ
Keith A. Bello - Tucson AZ
Michael T. Benhase - Tucson AZ
Donald M. Nordahl - Tucson AZ
Raymond E. Wilsey - Tucson AZ

Assignee:

International Business Machines Corporation - Armonk NY

International Classification:

G06F 900
G06F 1300
G06F 1208

US Classification:

395425

Abstract:

A cached DASD peripheral subsystem is operated in a so-called non-synchronous mode, that is, device operations are not synchronous to the host processor operations. A rate-changing buffer is interposed between the channel attachment for the host processor and the DASD, preferably having a storage capacity for one full DASD track of data. The rotational position for the data records being transferred in either direction, i. e. , write or read, are kept in the rate-changing buffer to be kept with the record being transferred through the rate-changing buffer. Each time the peripheral subsystem supplies ending status to the host processor and all records to be transferred are retentively stored in DASD, a record control field and the rotational position of the last record transferred in a chain of commands being transferred the rotational position of such last record, its type, and other control data are stored in a control store separate from any cache directory or track directory in cache. Such rotational position and type indicating information for the last record transferred is used for switching the modes of operation of the peripheral subsystem, error recovery, and for accommodating channel initiated retries.

US Patent:

51558149, Oct 13, 1992

Filed:

Aug 31, 1990

Appl. No.:

7/575735

Inventors:

Brent C. Beardsley - Tucson AZ
Keith A. Bello - Tucson AZ
Michael T. Benhase - Tucson AZ
Florence J. Clark - Tucson AZ
Paul W. Hunter - San Jose CA
Donald M. Nordahl - Tucson AZ

Assignee:

International Business Machines Corporation - Armonk NY

International Classification:

G06F 1312

US Classification:

395275

Abstract:

A control unit for DASD operation to transfer data between the device and a buffer and between a channel and a buffer. In that manner the channel and device are enabled to transfer data independently of each other. Mechanisms are provided for communication between the channel interface process in the control unit and the device interface process in the control unit. Some of these mechanisms are stored with the record in the buffer and others are stored in control storage. Principle communicating mechanisms include a device record pointer, a channel record pointer, a next operation field, a device state indicator, record control flags, and two buffer pointers.

US Patent:

59448024, Aug 31, 1999

Filed:

Aug 28, 1997

Appl. No.:

8/919853

Inventors:

Keith Anthony Bello - Tucson AZ
Donald Marvin Nordahl - Tucson AZ
Juan Antonio Yanes - Tucson AZ

Assignee:

International Business Machines Corporation - Armonk NY

International Classification:

G06F 1314

US Classification:

710 52

Abstract:

The present invention reduces the delay in the completion of transferring data from a data channel to an input/output device and the time a host unit is released from performing the data transfer function. A time reduction is realized by monitoring the current data transfer between the data channel and a buffer device to establish a transfer rate. The transfer rate is used to anticipate and coordinate the transfer of the last bit of data from the data channel to coincide with the receipt of the data by the input/output (I/O) unit, effectively eliminating buffer device delay and allowing the host unit to be released from performing the data transfer. In the preferred embodiment, the transfer of the last bit of data by the data channel occurs at substantially the same time as the last bit of data is received by the I/O unit.

US Patent:

54468728, Aug 29, 1995

Filed:

Jun 23, 1993

Appl. No.:

8/082349

Inventors:

Kathryn J. Ayres - Tucson AZ
Brent C. Beardsley - Tucson AZ
Keith A. Bello - Tucson AZ
Michael T. Benhase - Tucson AZ
Donald M. Nordahl - Tucson AZ
Alfred G. Torre - Lafayette CA
Bao T. Trieu - San Jose CA
Linda D. VanPatten - Tucson AZ

Assignee:

International Business Machines Corporation - Armonk NY

International Classification:

G06F 1100

US Classification:

395180

Abstract:

An error recovery process for a non-synchronous DASD control unit. A channel process within the control unit is able to operate on different fields from a device process within the control unit. Independent errors may be sensed by each process. The error recovery process provides for restarting only the trailing process and deferring handling of the error sensed by the leading process, whenever possible.