Abstract: Method, apparatus and program product are provided for rebuilding faulty metadata in a storage controller coupled to a host device. Faulty metadata may include metadata which no longer matches the associated customer data tracks stored on a DASD or other storage device. When an error in metadata is describing a first customer track is detected, a range of other customer tracks in which the error is also likely to have occurred is identified. The metadata tracks associated with the first customer track and the other customer tracks are selected to be invalidated. A command is received through a host interface, and the specified metadata tracks are invalidated while the controller remains on-line with the host and continues to process other host I/O operations. Subsequently, the invalidated metadata tracks are rebuilt. The disclosed method, apparatus and program product invalidate the faulty metadata with reduced impact on normal host/controller I/O operations.

Abstract: Method, apparatus and program product are provided for the invalidation of faulty metadata in a storage controller coupled to a host device. Faulty metadata may include metadata which no longer matches the associated customer data tracks stored on a DASD or other storage device. When faulty metadata is detected, metadata tracks are selected to be invalidated. A command is received through a host interface, without the controller being taken off-line from the host, and the specified metadata tracks are invalidated. Subsequently, the invalidated metadata tracks are rebuilt. The disclosed method, apparatus and program product invalidate the faulty metadata with reduced impact on normal host/controller I/O operations.

Abstract: A method, system and processor for substantially reducing the write penalty (or latency) associated with writes and/or destaging operations within a RAID 5 array and/or RAID 6 array. When a write or destaging operation is initiated, i.e., when modified data is to be evicted from the cache, an existing data selection mechanism first selects the track of data to be evicted from the cache. The data selection mechanism then triggers a data track grouping (DTG) utility, which executes a thread to group data tracks, in order to maximize full stripe writes. Once the DTG algorithm completes the grouping of data tracks to complete a full stripe, a fall-stripe write is performed, and parity is generated without requiring a read from the disk(s). In this manner, the write penalty is substantially reduced, and the overall write performance of the processor is significantly improved.

Abstract: A method is disclosed to manage a data cache. The method provides a data cache comprising a plurality of tracks, where each track comprises one or more segments. The method further maintains a first LRU list comprising one or more first tracks having a low reuse potential, maintains a second LRU list comprising one or more second tracks having a high reuse potential, and sets a target size for the first LRU list. The method then accesses a track, and determines if that accessed track comprises a first track. If the method determines that the accessed track comprises a first track, then the method increases the target size for said first LRU list. Alternatively, if the method determines that the accessed track comprises a second track, then the method decreases the target size for said first LRU list. The method demotes tracks from the first LRU list if its size exceeds the target size; otherwise, the method evicts tracks from the second LRU list.

Abstract: An apparatus and a method to allocate device adapter bandwidth, where that device adapter is disposed in an information storage and retrieval system capable of communicating with one or more host computers, and where that device adapter interconnects a data cache with information storage devices. The data storage and retrieval system receives a plurality of requests from the host computers to read information from, or to write information to, information storage devices. The method determines a read/write request ratio and a non-volatile storage utilization ratio. The method allocates device adapter bandwidth based upon the read/write request ratio and/or the non-volatile storage utilization ratio.

Abstract: A method to initialize information disposed in an information storage and retrieval system comprising a data cache and one or more information storage media comprising a plurality of addresses. The method receives an initialization command, where that initialization command comprises a range of addresses and, optionally, an initialization pattern, where the plurality of addresses includes the range of addresses. The method forms and saves state information, where that state information includes the initialization pattern, and generates and saves a plurality of indicators, where that plurality of indicators includes an indicator for each track comprising the range of addresses. The method sets each of those indicators to a first value thereby indicating special handling, and provides an ending status signal, such that the receiving step, forming step, generating step, setting step, and providing step are performed substantially synchronously.

Abstract: A storage system, method of managing a storage system and program product for managing a storage system. Cache fast write (CFW) modified data may be provided to cache in count-key-data (CKD) tracks with associated meta data. A synchronization flag is included on a storage device with associated meta data for each CKD track stored. The cache directory control block (CDCB) includes a CDCB synchronization flag for each CKD track in cache memory. A mismatch in the synchronization flags from a failure during a transfer to storage indicates a storage device loss of synchronization between an accessed CKD track and stored associated meta data.

Abstract: An apparatus and a method to allocate device adapter bandwidth, where that device adapter is disposed in an information storage and retrieval system capable of communicating with one or more host computers, and where that device adapter interconnects a data cache with information storage devices. The data storage and retrieval system receives a plurality of requests from the host computers to read information from, or to write information to, information storage devices. The method determines a read/write request ratio and a non-volatile storage utilization ratio. The method allocates device adapter bandwidth based upon the read/write request ratio and/or the non-volatile storage utilization ratio.

Abstract: A storage system, method of managing a storage system and program product for managing a storage system. Cache fast write (CFW) modified data may be provided to cache in count-key-data (CKD) tracks with associated meta data. A synchronization flag is included on a storage device with associated meta data for each CKD track stored. The cache directory control block (CDCB) includes a CDCB synchronization flag for each CKD track in cache memory. A mismatch in the synchronization flags from a failure during a transfer to storage indicates a storage device loss of synchronization between an accessed CKD track and stored associated meta data.