Abstract: Apparatus and associated method that stores first metadata only at the same addressable storage location of a computer readable medium as that where associated first user data is stored, and afterward satisfies a read request for the first user data by retrieving the first user data from the addressable location of the computer readable medium where the first metadata is stored if the first metadata has a first value, and by reconstructing the first user data from other metadata stored at another addressable location of the computer readable medium than where the first metadata is stored if the first metadata has a second value.

Abstract: A method is provided for storing and retrieving data in a network-attached data storage device by a cooperatively multitasking real time operating system configured to execute datapath routines and a general purpose operating system kernel configured to communicate with the network.

Abstract: Metadata architecture and associated methodology for a data storage system employing a grid-based storage capacity wherein each grid defines a storage unit in terms of a plurality of storage domains along one axis against one or more rows of a plurality of storage stripes along another axis, and wherein a grid grouping of two or more grids defines a sheet of data storage capacity. The metadata comprises identification information stored in a memory space characterizing an allocation status of the sheets in the storage capacity. A method is provided for allocating memory for the grid-based storage capacity comprising determining whether the allocation is associated with an existing logical device. If the determining step is associated with an existing logical device, then a logical device allocation map and a sheet allocation table are accessed to allocate a selected storage unit. Otherwise, a sheet allocation descriptor and a sheet allocation map are accessed to allocate a selected storage unit.

Abstract: An apparatus and associated method are provided for performing a storage transaction associated with a network I/O command by employing an ASIC having an interconnect selectively coupling a plurality of dedicated purpose function controllers in the ASIC to a policy processor via a list manager in the ASIC communicating on a peripheral device bus to which the policy processor is connected.

Abstract: Apparatus and method for command queue management of back watered requests. A selected request is released from a command queue, and further release of requests from the queue is interrupted when a total number of subsequently completed requests reaches a predetermined threshold.

Abstract: A data storage system and associated method are provided wherein a policy engine continuously collects qualitative information about a network load to the data storage system in order to dynamically characterize the load and continuously correlates the load characterization to the content of a command queue of transfer requests for writeback commands and host read commands, selectively limiting the content with respect to writeback commands to only those transfer requests for writeback data that are selected on a physical zone basis of a plurality of predefined physical zones of a storage media.

Abstract: Apparatus and method for accessing a virtual storage space. The space is arranged across a plurality of storage elements, and a skip list is used to map as individual nodes each of a plurality of non-overlapping ranges of virtual block addresses of the virtual storage space from a selected storage element.

Abstract: As apparatus and associated method for a dual active-active array storage system with a first controller with top level control of a first memory space and a second controller with top level control of a second memory space different than the first memory space. A seek manager residing in only one of the controllers defines individual command profiles derived from a combined list of data transfer requests from both controllers. A policy engine continuously collects qualitative information about a network load to both controllers to dynamically characterize the load, and governs the seek manager to continuously correlate each command profile in relation to the load characterization.

Abstract: A data storage system and associated method are provided wherein a policy engine continuously collects qualitative information about a network load to the data storage system in order to dynamically characterize the load and continuously correlates the load characterization to a command queue depth of data transfer requests.

Abstract: Apparatus and method for aggregating storage elements. In accordance with various embodiments, a virtual storage space is formed across a plurality of storage elements each comprising an array of data storage devices. A virtual controller comprises a first storage element aggregator (SEA) configured to issue a first command to a selected storage element in response to receipt by the first SEA of a first host command. The virtual controller further comprises a second SEA configured to concurrently issue a second command to the selected storage element in response to receipt by the second SEA of a second host command.

Abstract: Apparatus and method for arranging a virtual storage space with a cyclical wrapping grid function. The virtual storage space is formed from a physical memory and comprises a plurality of larger grains of selected storage capacity, each divided into a power of two number of smaller grains. Each of the larger grains are distributed across a non-power of two number of storage elements so that each of the storage elements receives the same number of smaller grains.

Abstract: Apparatus and method for highly efficient data queries. In accordance with various embodiments, a data structure is provided in a memory space with a first portion characterized as a virtual data space storing non-sequential entries and a second portion characterized as a first data array of sequential entries. At least a first sequential entry of the data array points to a skip list, at least a second sequential entry of the data array points to a second data array, and at least a third sequential entry points to a selected non-sequential entry in the first portion.

Abstract: A data storage system and associated method implement a HASTE with a policy engine that continuously collects qualitative information about a network load to the data storage system in order to dynamically characterize the load, and continuously correlates a command profile to a data storage device of the data storage system in relation to the characterization.

Abstract: A data storage system and associated method is provided within an enclosure supporting a self-contained plurality of discrete data storage devices configured for connecting with a network device via a network. The data storage system includes a redundant array of independent drives (RAID) container services module in the enclosure that allocates and manages a storage space of the data storage devices for storing primary and redundant data, and a policy engine in the enclosure that continuously and qualitatively characterizes the network load to the data storage system and manages a power distribution to each of the data storage devices based on a predicted utilization that differentiates between access commands for primary data and access commands for redundant data.

Abstract: A dual ported active-active array controller apparatus is provided having a first policy processor partnered with a first ISP having a first plurality of dedicated purpose FCs, a second policy processor partnered with a second ISP having a second plurality of dedicated purpose FCs, a communication bus interconnecting the ISPs, and programming instructions stored in memory and executed by the array controller to maintain the first policy processor in top level control of transaction requests from both the first plurality of FCs and the second plurality of FCs that are associated with network input/output (I/O) commands directed to a storage logical unit number (LUN) which the first ISP is a logical unit master of.

Abstract: A storage system is provided with an ASIC having an interconnect selectively coupling a plurality of dedicated purpose function controllers in the ASIC to a policy processor, via a list manager in the ASIC communicating on a peripheral device bus to which the policy processor is connected, and an event ring buffer to which all transaction requests from each of the plurality of function controllers to the policy processor are collectively posted in real time.

Abstract: A directory structure for a sparsely filled data container comprises a linked list, doubly linked list, skip list, or other non-fully populated list technique. One or more hierarchical levels of such lists may be used for sparsely filled directories. The directory structure may be converted to a conventional look-up table directory by reconstructing the directory when the directory becomes populated to certain point.

Abstract: An atomic write descriptor associated with stripe buffer list metadata.

Abstract: Disclosed is a data storage architecture that provides data regeneration following the failure of two storage domains and that provides conversion for RAID-6 to RAID-5 or RAID-0 without moving or copying any data. A storage grid comprising at least eight domains and twelve rows contains user data in a first contiguous portion and may contain row parity data in a second continuous portion and may contain vertical parity data in a third contiguous portion. In one embodiment data is arranged in row and vertical sets each comprising four data blocks such that each user data block is a member of one row set and is a member of one vertical set. In another embodiment sets comprise two blocks each.

Abstract: A data storage system is provided comprising memory allocation information associated with a change in a system configuration of memory allocation within a memory space, and means for updating the system configuration by saving the memory allocation information before updating the system configuration. A recovery record comprises memory allocation information associated with the change in system configuration of memory allocation, and a completion indicator comprises a first value if the memory allocation information is included in the system configuration and comprises a second value if the memory allocation information is not included in the system configuration.