Abstract: Methods and apparatuses for facilitating the management of multiple controller code versions for implementing operational aspects of storage system controllers are provided. In particular, multiple versions of storage controller code are loaded into the physical memory of a storage controller. The logical region in which a particular controller code version is loaded may be designated in metadata as a primary, secondary or other region. The controller code that is associated with a logical version designated as the primary region is selected by the storage controller for execution upon a storage controller reboot. Accordingly, time consuming copy operations are not required in order to switch between different versions of storage controller code.

Abstract: A method, device, and system are provided for the efficient transfer of snapshot data during a snapshot delete action. The snapshot data to be deleted may have an older version of the same snapshot and that older snapshot may need to access the data from the newer snapshot. Instead of copying all of the snapshot data of the snapshot that is being deleted to the older snapshot, only pointers to the data are copied to the older snapshot. Additionally, snapshot data can be accessed for read functions or the like while the snapshot pointers are being copied to the older snapshot.

Abstract: A data storage system configured for efficient mirroring of data between paired redundant controllers is provided. More particularly, in response to the receipt of customer data from a host for storage, a first controller segments the received customer data into one or more frames of data. In addition, the first controller determines or associates certain metadata for each frame of customer data, and inserts that metadata in the corresponding frame. The frames, including the metadata, are provided to a secondary controller. The secondary controller stores the customer data from a received frame in memory, and stores the corresponding metadata in another location of memory that is indexed to the location where the customer data was stored. The secondary controller may also associate a count value with each frame of data in order to distinguish the most recent frame of data should frames in memory have matching metadata.

Abstract: A method, device, and system are provided for the automatically assigning identification numbers or enclosure IDs to enclosures in a data storage system. Each enclosure is assigned a unique enclosure ID that can be used to reference the enclosure in the data storage system. The enclosure IDs are generated and assigned to enclosures based on the network topology. Specifically, each enclosure is assigned an enclosure ID that not only uniquely identifies the enclosure but the enclosure ID can be used to determine the location of the enclosure in the data storage system.

Abstract: A network storage controller for transferring data between a host computer and a storage device, such as a redundant array of inexpensive disks (RAID), is disclosed. The network storage controller includes at least one channel interface module which is adapted to be connected to the host computer and storage device. The channel interface module is connected to a passive backplane, and selectively transfers data between the host computer and storage device and the passive backplane. The network storage controller also includes at least one controller memory module, attached to the passive backplane. The controller memory module communicates with the channel interface module via the passive backplane, and processes and temporarily stores data received from the host computer or storage device. In applications where redundancy is required, at least two controller memory modules and at least two channel interface modules are used.

Abstract: Methods and apparatuses for providing a data storage system having snapshot restore capabilities are provided. In particular, snapshots may be taken to represent a state of a storage volume at different times. The state of the storage volume may be returned to the state represented by any snapshot even while the storage volume continues to accept read and write operations. Furthermore, these features are provided in the context of a sparse snapshot structure, according to which multiple copies of individual data chunks are not maintained by the data storage system.

Abstract: The present invention is directed to a data storage system utilizing a number of data storage devices. Each of the data storage devices stores primary and mirrored copies of data. Furthermore, the data is arranged such that no one data storage device stores both the primary and mirrored copies of the same chunk of data. Data may be striped across the storage devices such that stripes containing primary copies of data chunks are interleaved with stripes containing mirrored copies of data chunks.

Abstract: A direct memory access (DMA) engine has virtually all control in connection with data transfers that can involve one or both of primary and secondary controllers. The DMA engine receives a command related to a data transfer from a processor associated with the primary controller. This command causes the DMA engine to access processor memory to obtain metadata therefrom. In performing a DMA operation, the metadata enables the DMA engine to conduct data transfers between local memory and remote memory. In performing exclusive OR operations, the DMA engine is involved with conducting data transfers using local memory.

Abstract: The present invention provides for a data storage system having a number of virtual storage devices. Each of the virtual storage devices may include a number of physical storage devices. The physical storage devices need not be separately addressable by a host system. Each virtual storage device unit may comprise a field replaceable unit encompassing no more than a single virtual storage device. Physical storage devices included in a virtual storage device that are not in active use may be powered down, even while one or more other physical devices included in that virtual storage device are powered up.

Abstract: Methods and apparatuses for providing a data storage system having snapshot restore capabilities are provided. In particular, snapshots may be taken to represent a state of a storage volume at different times. The state of the storage volume may be returned to the state represented by any snapshot even while the storage volume continues to accept read and write operations. Furthermore, these features are provided in the context of a sparse snapshot structure, according to which multiple copies of individual data chunks are not maintained by the data storage system.

Abstract: A method and apparatus for obscuring data held on a storage device associated with a storage system controller are provided. Data is obscured by swapping bit values according to a scrambling key, before the unit of data is stored on the storage device. Furthermore, multiple swaps or translations of bit values can be performed in sequence on a single unit of data. In order to descramble a unit of data, the translations of bit values applied during scrambling are performed in reverse order. Alternatively or in addition, data can be obscured by scrambling the bit values of an address associated with a unit of data.

Abstract: A data storage system configured for efficient operation in a single controller mode and to facilitate an upgrade from single controller operation to dual redundant active-active controller operation is provided. More particularly, a first controller having a segmented write cache is provided. The first segment of the write cache is associated with logical unit numbers (LUNs) owned by the first controller. The second segment is associated with LUNs that are designated as being owned by a second controller. During single controller operation, the segments of the write cache operate as primary write cache. The system may be converted to dual redundant controller operation by adding a second controller having a write cache segmented like the write cache of the first controller. Upon adding a second controller, primary control of the LUNs owned by or zoned to the second controller is taken over by the second controller.

Abstract: The present invention is directed to a data storage system utilizing a number of data storage devices. The data storage system features one or more storage device sleds, which may each carry multiple storage devices. Each storage device sled and its interconnected storage devices may comprise a field replaceable unit. In response to the detection of a failure associated with a field replaceable unit, information related to that failure may be stored in memory or storage associated with the field replaceable unit. Repair personnel may access the stored information in order to positively identify the failed component of the field replaceable unit in connection with the repair or replacement of that component, in order to return the field replaceable unit to service.

Abstract: A data storage system that includes first and second controllers is provided. Data is mirrored from one controller to the other controller according to different steps depending on the amount of data to be mirrored. When the data to be mirrored is less than or equal to a predetermined number of bytes, one less interrupt is generated than when the data to be mirrored is greater than the predetermined number of bits.

Abstract: The present invention provides for a data storage system having a number of virtual storage devices. Each of the virtual storage devices may include a number of physical storage devices. The physical storage devices need not be separately addressable by a host system. Each virtual storage device unit may comprise a field replaceable unit encompassing no more than a single virtual storage device. Physical storage devices included in a virtual storage device that are not in active use may be powered down, even while one or more other physical devices included in that virtual storage device are powered up.

Abstract: A network storage controller for transferring data between a host computer and a storage device, such as a redundant array of inexpensive disks (RAID), is disclosed. The network storage controller includes at least one channel interface module which is adapted to be connected to the host computer and storage device. The channel interface module is connected to a passive backplane, and selectively transfers data between the host computer and storage device and the passive backplane. The network storage controller also includes at least one controller memory module, attached to the passive backplane. The controller memory module communicates with the channel interface module via the passive backplane, and processes and temporarily stores data received from the host computer or storage device. In applications where redundancy is required, at least two controller memory modules and at least two channel interface modules are used.

Abstract: A method is disclosed for recovering data from a RAID system after a transient failure. After a transient failure, the cause of the failure is corrected and a user initiates a trust array command. The RAID controller receives the trust array command and performs several modifications to the disk metadata. First, the partition age metadata field is synchronized. Second, the primary dead partition map metadata field is cleared. Third, the partition status metadata field is set to initialized. Following the metadata modifications, the RAID controller verifies that it can access all of the drives in the array. If all drives are accessible, the array is on-line and fault tolerant without the need for re-constructing a drive within the array, or re-creating the array. If one drive remains inaccessible, data is available from the array, and the array is in a critical state. If two or more drives remain inaccessible, the array remains off-line and a partial recovery may be attempted.

Abstract: A storage array comprised of a number of storage drives is provided with a controller to control zero initialization of the storage drives. The zero initialization involves writing zeros to all the storage drives in the array before user data or other information is written thereto. Each storage drive has a priority associated with accessing and using a bus subsystem that provides the communication link between the array of storage drives and the controller. A number of write operations are conducted during the zero initialization process to each storage drive in the array. A first write operation is performed by each storage drive before a second write operation is performed. Substantially equal usage of the bus subsystem by all the storage drives in the array is achieved in order to fully utilize the available bandwidth of the bus subsystem and reduce the time required to complete the zero initialization.

Abstract: A network storage controller for transferring data between a host computer and a storage device, such as a redundant array of inexpensive disks (RAID), described. The network storage controller includes at least one channel interface module which is adapted to be connected to the host computer and storage device. The network storage controller also includes at least one controller memory module, attached to a passive backplane. The controller memory module communicates with the channel interface module. In applications where redundancy is required, at least two controller memory modules and at least two channel interface modules are used. The controller memory modules may mirror data between one another using the passive backplane and a shared communication path on the channel interface modules.

Abstract: A system and method for efficient parity mirroring between controllers of an active-active controller pair in a redundant array of inexpensive disks (RAID) system is disclosed. When a second controller in an active-active controller pair receives new data to be written to a disk array, it mirrors the new data to a first controller in the active-active controller pair. The second controller then computes new parity for the data stripe associated with the new data. The second controller then opens a parity log and mirrors logical block address (LBA) information for the new data to a first controller in the active-active controller pair. In the event of a failure of the second controller after mirroring the LBA information and prior to completing the write operation, the first controller uses the LBA information to complete the write operation, assuring that the new data and new parity are properly stored on the disk array.