International Business Machines Corporation

Kelly Scott Carpenter

Jeffrey Mark Nick

Michael D Swanson

Jimmy Paul Strickland

Wendell W Wilkinson

Gary M King

Gerard Maclean Dearing

Kevin F Smith

Kenneth Michael Kapulka

Marc Kenneth Duquette

A method and system for transparently recovering from a coupling facility failure are disclosed. In one method embodiment, the present invention determines, following the failure of a coupling facility, which data was previously assigned to that coupling facility. The present embodiment then prevents access to that failed coupling facility. Next, the present method embodiment selects a new storage location for the data which was previously assigned to the failed coupling facility. The present embodiment then assigns the data previously assigned to the failed coupling facility to a new storage location. In the present invention, the aforementioned steps are performed without requiring preallocation of white space in an alternate coupling facility.

Method and system for recovery from a coupling facility failure without preallocating space

A data processing system dynamically balances allocation of storage areas in a shared coupling facility that is devoted to storage of directory entries and data blocks. Each directory entry includes information regarding the validity of a data block that is locally stored by one or more processor modules in the data processing system. The system includes a coupling facility having a cache memory wherein a first portion is allocated to storage of data blocks and a second portion is allocated to storage of directory entries. Each directory entry, associated with a data block, indicates the validity or invalidity of data contained in a copy of the data block maintained by a connected computer module in its local memory. Each computer module, upon requiring a first data block and determining that (i) the first data block is present in its local memory (i.e., a buffer 'hit'), but (ii) is not marked valid and (iii) is not present in the coupling facility (i.e., a cache 'miss'), accesses the first data block from a disk store, even though the first data block in its local memory may be valid. A memory allocation procedure controls the sizes of the first portion and second portion of the cache memory. The procedure (i) maintains a record, per unit of time, of a number of cache 'miss' occurrences, (i.e., a cache 'miss' rate) and an estimate of the number of false invalidation occurrences (i.e., a false invalidation rate); derives a first order derivative of the sum of cache miss-rate and the estimated false invalidation rate and (iii) employs the derivative to adjust the sizes of the first portion and second portion of the cache memory so as to minimize the sum of the expected miss and false invalidation rate values.

Method and apparatus for determining a desirable directory/data block

A high-speed cache is shared by a plurality of independently-operating data systems in a multi-system data sharing complex. Each data system has access both to the high-speed cache and to lower-speed, upper-level storage for obtaining and storing data. Management logic in the shared high-speed cache is provided to meet the serialization and data coherency requirements of the data systems when sharing the high speed cache as a store-multiple cache in a multi-system environment.

Coherence controls for store-multiple shared data coordinated by cache

Growing community of inventors

Elgin, TX, United States of America

Kelly Scott Carpenter