Abstract: Methods and structure for managing cache memory for a storage controller. One exemplary embodiment a Redundant Array of Independent Disks (RAID) storage controller. The storage controller includes an interface operable to receive Input/Output (I/O) requests from a host, a Direct Memory Access (DMA) module, a memory comprising cache data for a logical volume, and a control unit. The control unit is able to generate Scatter Gather Lists (SGLs) that indicate the location of cache data for incoming read requests. Each SGL is stored in the memory, and at least one SGL points to cache data that is no longer indexed by the cache. The control unit is also able to service an incoming read request based on the SGL, by directing the DMA module to transfer the cache data that is no longer indexed to the host.

Abstract: Methods and structure for formatting and processing Scatter Gather Lists (SGLs). One exemplary embodiment is a storage controller that includes a cache memory storing data for a logical volume, and a control unit. The control unit is able to service an Input/Output (I/O) request based on a Scatter Gather List (SGL) that refers to the cache memory, the SGL comprising multiple entries that each include a flag field and an identifier (ID) field. The entries are assigned to categories that are each associated with a different set of stored processing instructions. The control unit is able to identify a category for an entry based on a combination of both flag field and ID field for the entry, and the control unit is able to process the entry using the set of instructions associated with the identified category.

Abstract: Methods and structure for managing cache memory for a storage controller. One exemplary embodiment a Redundant Array of Independent Disks (RAID) storage controller. The storage controller includes an interface operable to receive Input/Output (I/O) requests from a host, a Direct Memory Access (DMA) module, a memory comprising cache data for a logical volume, and a control unit. The control unit is able to generate Scatter Gather Lists (SGLs) that indicate the location of cache data for incoming read requests. Each SGL is stored in the memory, and at least one SGL points to cache data that is no longer indexed by the cache. The control unit is also able to service an incoming read request based on the SGL, by directing the DMA module to transfer the cache data that is no longer indexed to the host.