Abstract: A method for maintaining reliable communication between a command initiator and a target device is provided. After the command initiator detects an error corresponding to the target device and a path between the command initiator and the target device, the command initiator performs a downshift evaluation. The initiator maintains a transmission speed if the downshift evaluation determines that forgoing a transmission speed downshift is required, and reduces the transmission speed if the downshift evaluation determines that transmission speed downshift is required. The command initiator then logs the downshift evaluation result and reports any transmission speed change to a user.

Abstract: A method for maintaining reliable communication on a bidirectional communication link is provided. A receiver on the bidirectional communication link detects an error and maintains a count of detected errors. The transmitter on the bidirectional communication link polls the receiver in order to determine the count of detected errors, and performs a downshift evaluation for the bidirectional communication link. In response to performing the downshift evaluation for the bidirectional communication link, the transmitter maintains a transmission speed of the bidirectional communication link if the downshift evaluation determines that forgoing transmission speed downshift is required for the bidirectional communication link, and reduces the transmission speed of the path if the downshift evaluation determines that transmission speed downshift is required for the bidirectional communication link.

Abstract: A method and device for managing snapshot data is provided. Snapshots may be created having a preserved data area and a write data area. The preserved data area is used to maintain snapshot data corresponding to the point-in-time when the snapshot was created while the write data area is used to facilitate host read/write access to the snapshot. By maintaining two separate areas, the snapshot can be written to without altering the point-in-time representation of the snapshot.

Abstract: A data storage system, device, and method are provided for replicating data between different data storage systems or appliances. More specifically, the present invention affords communications between heterogeneous data storage systems that potential employ different communication protocols. A bridging communication protocol is utilized by one or both storage systems in order to accommodate different communication protocols. Alternatively, a storage appliance connecting the data storage systems may employ the bridging communication protocol.

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, device, and method are provided for replicating data between different data storage systems or appliances. More specifically, the present invention allows an initiating data storage device to pull data from a target data storage device. Thus, the storage device that is supplying the data can act as a target and does not require the additional software inherent in being an initiator.

Abstract: A storage controller that operates under elevated temperature conditions includes a memory, a memory controller, and a CPU that detects a temperature of the memory controller has exceeded a threshold while operating at a first frequency and responsively places the memory into self-refresh mode, reduces the memory controller frequency to a second frequency, and then takes the memory out of self-refresh mode. The clock frequency of a bus bridge or communications link circuit may also be reduced when their temperatures exceed a threshold. The bus bridge may deny access to requestors of access to the memory while the frequency is being reduced. Message transfers on a communications link between redundant storage controllers in a system may be suspended while the link frequency is being reduced. Finally, the system may fail over to one controller while the other controller reduces the frequencies and then fail back.

Abstract: A data storage system with a controller that receives shock data from a shock detection sensor and methods utilizing such a controller are provided. The data storage system controller receives information or signals regarding shock events from a shock sensor, enabling the data storage system controller to take remedial action. The particular remedial action taken may be dependent on the severity of the detected shock event. The data storage system controller may receive information regarding shock events from shock sensors provided separately from the data storage system controller, allowing the data storage system controller to take remedial action that is tailored to the locale of a shock event.

Abstract: A data storage system controller having a shock detection sensor and methods utilizing such a controller are provided. The data storage system controller receives information or signals regarding shock events from the associated shock sensor, enabling the data storage system controller to take remedial action. The particular remedial action taken may be dependent on the severity of the detected shock event. The data storage system controller may also receive information regarding shock events from shock sensors provided separately from the data storage system controller, allowing the data storage system controller to take remedial action that is tailored to the locale of a shock event.

Abstract: A method, device, and system are provided for rollback of a master volume in a data storage system. More specifically, when a rollback is requested, snapshots that are involved in the rollback can be deleted during the rollback. This is accomplished by deleting the snapshot partition but not the actual snapshot data. Rather, the snapshot data is retained until the rollback is complete incase some of the snapshot data needs to be written to the master volume as part of the rollback.

Abstract: Methods and systems for managing user access to a storage system controller are provided. In particular, user login requirements and permissions are administered, and individual user and external user interface pairs are tracked, through a user table and a session table established as part of the storage system controller. The external user interfaces may be interconnected to the storage system controller through different networks and/or protocols. User authentication and access levels are established with reference to a user table, while sessions for different user and external interface pairs are maintained in the session table.

Abstract: A write-caching RAID controller includes a CPU that manages transfers of posted-write data from host computers to a volatile memory and transfers of the posted-write data from the volatile memory to a redundant array of storage devices when a main power source is supplying power to the RAID controller. A memory controller transfers the posted-write data received from the host computers to the volatile memory and transfers the posted-write data from the volatile memory for transfer to the redundant array of storage devices as managed by the CPU. The memory controller flushes the posted-write data from the volatile memory to the non-volatile memory when main power fails, during which time capacitors provide power to the memory controller, volatile memory, and non-volatile memory, but not to the CPU, in order to reduce the energy storage requirements of the capacitors.

Abstract: The verification of fault-tolerant connections between redundant controller pairs and nodes is provided. In particular, a node identifier seen at one port of the controllers is compared to the node identifier seen at another port of the controllers. In response to determining that proper connections have not been made, an error or warning signal may be generated. In addition, where supported by dynamic port configuration, the ports of the controllers may be reconfigured in response to the comparison to effect proper connections. In response to determining that proper connections have been made, a signal verifying that proper connections have been made may be generated.

Abstract: A method, device, and system for resetting snapshots are provided. The reset of a snapshot incorporates the traditional snapshot delete and snapshot create operations into a single operation. Additionally, a snapshot created under the reset operation may receive an array partition from a snapshot being deleted under the same snapshot reset operation thereby retaining its identifying characteristics.

Abstract: A RAID controller uses a method to identify a storage device of a redundant array of storage devices that is returning corrupt data to the RAID controller. The method includes reading data from a location of each storage device in the redundant array a first time, and detecting that at least one storage device returned corrupt data. In response to detecting corrupt data, steps are performed for each storage device in the redundant array. The steps include reading data from the location of the storage device a second time without writing to the location in between the first and second reads, comparing the data read the first and second times, and identifying the storage device as a failing storage device if the compared data has a miscompare. Finally, the method includes updating the location of each storage device to a new location and repeating the steps for the new location.

Abstract: A method and device for performing a volume copy is provided. The volume copy method allows access to both the Volume Copy Source and Volume Copy Target while the volume copy process is occurring. This allows a system administrator to initiate a volume copy without worrying that host access to the Volume Copy Source and Volume Copy Target will be interrupted.

Abstract: A method, device, and system are provided for re-initializing a backing store in a data storage system. More specifically, when all snapshots associated with a specified backing store are either being deleted or are marked for deletion the backing store is re-initialized rather than deleting each snapshot independently. The re-initialization of the backing store provides for a quicker way to delete all snapshots than could previously be achieved when each snapshot was deleted independently.

Abstract: Methods and systems for preventing permanent data loss due to a single failure in an array of storage devices are described. In particular, a defective memory block is detected and data that was on the now defective memory block is reconstructed using backup data in the array. The reconstructed data is stored in a replacement memory block, without requiring the rewriting of data in non-defective memory blocks. The information mapping the defective memory block to the replacement memory block may be stored as metadata on a storage device.

Abstract: Methods and systems for managing user access to a storage system storage controller are provided. In particular, user login requirements and permissions are administered, and individual user and external user interface pairs are tracked, through a user table and a session table established as part of the storage system controller. The external user interfaces may be interconnected to the storage system controller through different networks and/or protocols. Notification of events to external interfaces is performed as part of a task running on the storage system controller. In particular, an event notification manager determines whether notification of an event should be provided in connection with active sessions, with the result that the storage system controller only sends notification of events that have not previously been reported to a user and external interface pair.

Abstract: A method and device for cloning snapshots is provided. A new snapshot can be created by cloning an existing snapshot. The clone snapshot may use the preserved data of the existing snapshot, thereby obviating the need to copy the preserved data. Additionally, the clone snapshot may be created with a data structure for storing write data. Since the clone snapshot initially has no write data to store, the creation of the entire clone snapshot can be accomplished without copying any preserved data or write data from the existing snapshot, thereby increasing the efficiency with which a clone snapshot can be created.