International Business Machines Corporation

Vern J Legvold

Gail Andrea Spear

Brent Cameron Beardsley

Susan Kay Candelaria

Lawrence Carter Blount

Douglas A Martin

Peter L Leung

Dennis Albert Kukula

Steven C Cowley

An improved storage controller and method for storing and recovering data. The storage controller includes a first cluster for directing data from a host computer to a storage device and a second cluster for directing data from a host computer to a storage device. A first cache memory is connected to the first cluster and a second cache memory is connected to the second cluster. A first nonvolatile memory is connected to the second cluster and a second nonvolatile memory is connected to the first cluster. The first and second cache memories and the first and second nonvolatile stores are thus 'cross-coupled' to the first and second clusters to provide improved data recovery capability. Data is directed to the first cache and backed up to the first nonvolatile memory in a first operational mode. In the event of failure of the first nonvolatile memory, data is recovered from the first cache memory. In a particular embodiment, in the event of failure of the first nonvolatile memory, data is directed from the first cache memory to the second cache memory. The cache memories and nonvolatile stores may also be formed on separate power boundaries. By allowing for use of the first cache after failure of an associated nonvolatile memory, a system and technique for mitigating performance degradation in a storage control unit due to a failure in nonvolatile memory associated therewith may be obtained.

Storage controller and method for improved failure recovery using

A system for automatically installing new processor control code in a computing system running old processor control code with minimal disruption in the operation thereof. The new code is loaded into the computing system and compared to the old code to identify values of a plurality of updating variables. Changes in the operation of the computing system are effected based on the values of the updating variables without disrupting the operation thereof. In a specific embodiment, the inventive system includes microcode in which resource management variables are labeled and given predetermined values. The resource management variables are compared to corresponding variables in the old code to determine which resources to control to effect an updating of the system. Thus, substantial changes in microcode are effected automatically and without disruption.

System for installing processor control code

A system and technique for storing data in a cache memory in record format and in track format. Space is allocated in cache memory for the storage of data in track format. Additional space is allocated for the storage of data in record format. Data is stored in both formats. The most current data is identified and addresses are generated for each record of data. Access to individual records of data is facilitated through a track information block in which pointers are stored for the most current records whether stored in track format or record format. The track information block facilitates a rapid storage and retrieval of data in either format. In a specific implementation, data is stored in either format in cache using a scatter index table. The scatter index table and associated track directory entries are stored in a shared control array. Each track directory entry points to a track slot header in a cache. The track slot header points to an area (segment) in the cache memory in which selected data resides. The track slot header also points to a track information block associated with the selected segment. The track information block identifies the location selected records in the segment in track format or record format.

Track and record mode caching scheme for a storage system employing a

Improved system for destaging data from a nonvolatile memory. The system is operative after a failure of an associated first cache memory for which the nonvolatile memory stores backup data. The invention is adapted to scan the nonvolatile memory to identify control data stored therein. Next a directory structure is built from control information in the nonvolatile memory which is used to provide rapid access to data stored therein. In a particular implementation, the directory structure is stored as a plurality of pointers in data storage space allocated in a second cache. Data may then be destaged from the nonvolatile memory in a more efficient manner by which records from a particular track are grouped together.

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Tucson, AZ, United States of America

Vern J Legvold