International Business Machines Corporation

Dennis R Martin

Michael James McDermott

Robert H Satin

Robert L Wenger

Stuart D Plumlee

Michael Steven Faunce

Duc H Nguyen

Thomas Richard Crowley

A method for recovering a computer system from a loadsource direct access storage device located at a remote location. In accordance with the method and system of the present invention, after a catastrophic damage and the installation of a local loadsource direct access storage device, an indicator within the local loadsource direct access storage device is set such that the local loadsource direct access storage device cannot be utilized for initial program load. Thereafter, the contents of the entire loadsource direct access storage device located at a remote location are copied to the replacement local loadsource direct access storage device. The indicator within the replacement local loadsource direct access storage device is reset such that the replacement local loadsource direct access storage device can be utilized for initial program load again. Finally, an initial program load is performed from the replacement local loadsource direct access storage device.

Method and system for recovering a computer system from a loadsource located at a remote location

DASD failures occurring on sector boundaries currently go undetected. While this sort of problem can occur at any time, it usually occurs when the program executing on the computer system's processor is operating on a multisector piece of data and periodically updating that information in auxiliary storage so that the copy in auxiliary storage is relatively up to date with the changes being made by the program. The storage management mechanism of the present invention solves the problem of sector boundary write failures by associating a sequence number with each piece of multisector data. Essentially, the sequence number becomes a property of the particular piece of data itself. When the mechanism retrieves the information from disk, it checks to make sure that all the sequence numbers match. If they do not, a data integrity problem has been detected.

Storage management mechanism that detects write failures that occur on

A method for updating mass storage device configuration records during a configuration change within a computer system is disclosed. A unit configuration record is stored in a system mass storage device. The unit configuration record is unique to each system and it includes a configuration identification, a sequence number and an alteration count table. In addition, a logical device identifier is stored in each mass storage unit within the system. The logical device identifier is unique to each mass storage device unit and it includes a configuration identification, a unit number and an alteration count. If a configuration update is necessary, the corresponding alteration count of the unit configuration record is first incremented, a new logical device identifier is then built with the new alteration count, and finally the new logical device identifier is written to a mass storage device that requires update. After the completion of configuration update, the sequence number is incremented, the updated information is then merged with the functioning copy of unit configuration record and the merged copy is subsequently written on to the system mass storage device. This invention allows a logical configuration change to be made even when the mass storage device of a configured set is unavailable, and thereby eliminating the restriction of all configured mass storage devices must be operational in order to perform a logical configuration change as required by the prior arts.

Method and system for mass storage device configuration management

A method of pairing disk units in a computer system where mirroring is desirable is disclosed. Where possible, disk units are paired with other disk units located on a different bus. This provides the highest level of protection against inaccessible data due to data loss or failure of a component in the computer system. Where this is not possible, the remaining disk units are paired with disk units located on a different I/O processor, a different controller, or a different disk enclosure. Where none of these pairings are possible, the remaining disk units fall below the threshold level of protection and therefore cannot be paired within the segment. Any disk units that could not be paired are placed on a spare list. Several attempts are made to pair up disk units on the spare list. If all of these attempts fail, the paired disk units with the lowest level of protection are broken apart and added to the spare list, where attempts are again made to pair up the disk units on the spare list. After all units are paired, a pair of disk units is compared with other pairs of disk units to see if the level of protection can be increased by swapping mates. This comparison of pairs of disk units is repeated until the level of protection is optimized. Each time the computer system is started, a check is made to determine if a configuration change resulted in a lower level of protection. If so, the user is asked if he would like the disk units on the computer system to be re-paired to increase the level of protection.

Computer controlled optimized pairing of disk units

A method of pairing disk units in a computer system where mirroring is desirable is disclosed. Where possible, disk units are paired with other disk units located on a different bus. This provides the highest level of protection against inaccessible data due to data loss or failure of a component in the computer system. Where this is not possible, the remaining disk units are paired with disk units located on a different I/O processor, a different controller, or a different disk enclosure. Where none of these pairings are possible, the remaining disk units fall below the threshold level of protection and therefore cannot be paired within the segment. Any disk units that could not be paired are placed on a spare list. The paired disk units with the lowest level of protection are broken apart and added to the spare list, where attempts are again made to pair up the disk units on the spare list. After all units are paired, a pair of disk units is compared with other pairs of disk units to see if the level of protection can be increased by swapping mates. This comparison is repeated until the level of protection is optimized. Each time the computer system is started, a check is made to determine if a configuration change resulted in a lower level of protection. If so, the user is asked if he would like the disk units on the computer system to be re-paired to increase the level of protection.

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Rochester, MN, United States of America

Dennis R Martin