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.

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.

Abstract: Methods and structure for redirecting writes in Redundant Array of Independent Disks (RAID) systems are provided. One exemplary embodiment is a RAID controller that includes a memory and a control unit. The memory is able to store mapping information that correlates Logical Block Addresses of a RAID volume with physical addresses of storage devices. The control unit is able to generate a request to write volume data to at least one of the physical addresses, to determine that a storage device has failed to complete the request, to alter the mapping information by correlating Logical Block Addresses for the request with physical addresses of a spare storage device, to redirect the request to the spare storage device, and to rebuild remaining Logical Block Addresses that are correlated with the storage device that failed.

Abstract: Embodiments herein provide for dynamic storage system configuration. In one embodiment, a storage controller is operable to configure a storage volume from a plurality of storage devices. The storage controller includes an interface operable to receive a first write I/O request from a host system, and to extract a storage configuration attribute from the first write I/O request. The storage controller also includes a processor communicatively coupled to the interface and operable to identify a storage configuration required by the first write I/O request based on the storage configuration attribute, to determine whether the storage volume comprises the required storage configuration of the first write I/O request, and to configure a portion of the storage volume according to the storage configuration required by the first write I/O request in response to a determination that the storage volume does not comprise the required storage configuration.

Abstract: Methods and structure for coordinating between Redundant Array of Independent Disks (RAID) storage controllers are provided. An exemplary system includes a RAID controller. The RAID controller includes a Peripheral Component Interconnect Express (PCIe) interface, a Serial Attached Small Computer System Interface (SAS) port operable to communicate with another RAID controller, and a command unit. The command unit is able to direct the interface to contact another PCIe interface at the other controller, to acquire an identifier of the other controller stored in a PCIe Inbound Map (PIM) for the other interface, and to activate a feature for the controller that enables cooperative management of storage devices between the controller and the other controller, if the identifier of the other controller matches discovery information maintained at the controller.

Abstract: Methods and structure for migrating logical volumes are provided. The system includes a Redundant Array of Independent Disks controller, which includes a Peripheral Component Interconnect Express interface, a Serial Attached Small Computer System Interface port operable to communicate with another Redundant Array of Independent Disks controller, and a command unit. The command unit is able to direct the interface to access another Peripheral Component Interconnect Express interface at the other controller, to synchronize with Disk Data Format information from a Peripheral Component Interconnect Express Inbound Map of the other interface, to detect that the other controller has failed, and to utilize the Disk Data Format information to migrate a logical volume from the other controller to the controller.

Abstract: Clustered storage systems and methods are presented herein. One clustered storage system includes a logical volume comprising first and second pluralities of storage devices. The first plurality of storage devices is different from the second plurality of storage devices and includes at least the same data as the second plurality of devices. The storage system also includes a first storage node operable to process first I/O requests to the first plurality of storage devices and a second storage node communicatively coupled to the first storage node and operable to process second I/O requests to the second plurality of storage devices. An I/O request of the first I/O requests initiates a redirection condition that the first storage node detects. Then, based on the redirection condition, the first storage node directs the second storage node to process data of the I/O request.

Abstract: A controller for maintaining data consistency without utilizing region lock is disclosed. The controller is connected to multiple physical disk drives, and the physical disk drives include a data portion and a parity data portion that corresponds to the data portion. The controller can receive a first input/output command (I/O) from a first computing device for writing write data to the data portion and a second I/O command from a second computing device for accessing data from the data portion. The controller allocates a first buffer for storing data associated with the first I/O command and allocates a second buffer for storing data associated with a logical operation. The controller initiates a logical operation that comprises an exclusive OR operation directed to the write data and the read data to obtain resultant exclusive OR data and copies the write data to the data portion.

Abstract: Methods and structure for coordinating between Redundant Array of Independent Disks (RAID) storage controllers are provided. An exemplary system includes a RAID controller. The RAID controller includes a Peripheral Component Interconnect Express (PCIe) interface, a Serial Attached Small Computer System Interface (SAS) port operable to communicate with another RAID controller, and a command unit. The command unit is able to direct the interface to contact another PCIe interface at the other controller, to acquire an identifier of the other controller stored in a PCIe Inbound Map (PIM) for the other interface, and to activate a feature for the controller that enables cooperative management of storage devices between the controller and the other controller, if the identifier of the other controller matches discovery information maintained at the controller.

Abstract: Methods and structure for migrating logical volumes are provided. The system includes a Redundant Array of Independent Disks controller, which includes a Peripheral Component Interconnect Express interface, a Serial Attached Small Computer System Interface port operable to communicate with another Redundant Array of Independent Disks controller, and a command unit. The command unit is able to direct the interface to access another Peripheral Component Interconnect Express interface at the other controller, to synchronize with Disk Data Format information from a Peripheral Component Interconnect Express Inbound Map of the other interface, to detect that the other controller has failed, and to utilize the Disk Data Format information to migrate a logical volume from the other controller to the controller.

Abstract: Methods and structure for redirecting writes in Redundant Array of Independent Disks (RAID) systems are provided. One exemplary embodiment is a RAID controller that includes a memory and a control unit. The memory is able to store mapping information that correlates Logical Block Addresses of a RAID volume with physical addresses of storage devices. The control unit is able to generate a request to write volume data to at least one of the physical addresses, to determine that a storage device has failed to complete the request, to alter the mapping information by correlating Logical Block Addresses for the request with physical addresses of a spare storage device, to redirect the request to the spare storage device, and to rebuild remaining Logical Block Addresses that are correlated with the storage device that failed.

Abstract: Clustered storage systems and methods are presented herein. One clustered storage system includes a logical volume comprising first and second pluralities of storage devices. The first plurality of storage devices is different from the second plurality of storage devices and includes at least the same data as the second plurality of devices. The storage system also includes a first storage node operable to process first I/O requests to the first plurality of storage devices and a second storage node communicatively coupled to the first storage node and operable to process second I/O requests to the second plurality of storage devices. An I/O request of the first I/O requests initiates a redirection condition that the first storage node detects. Then, based on the redirection condition, the first storage node directs the second storage node to process data of the I/O request.