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: 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 data storage control unit is coupled to one or more host devices and to one or more physical storage units, the physical storage units collectives configured as a plurality of logical storage ranks. The storage control unit receives and processes write requests from the host devices and directs that data updates be stored in a temporary storage. The data updates are subsequently destaged to the logical ranks. Write requests are processed at a predetermined rate relative to the rate at which destages are performed (destage mode or rate). The storage control unit evaluates workload conditions of the temporary storage and modifies the destage mode if the temporary storage is in danger of becoming backlogged or if an actual backlog is created, thereby applying a “throttle” to the host write requests. Thus, method, apparatus and program product are provided to dynamically modify a level of throttling whereby through-put of a host device is substantially maintained.

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.