Abstract: A data synchronization method (for a redundant data storage arrangement in which there are at least a primary storage entity and mirroring first and second remote storage entities in communication therewith, respectively, writes to the first and second remote storage entities being tracked via respective first and second sidefiles, the first and second storage entities having different levels of write-currency relative to each other) may include: comparing the first sidefile with the second sidefile; and updating writes stored at the second remote storage entity based upon the comparison of the first and second sidefiles.

Abstract: Various method and system embodiments of the present invention employ enhanced journal-based resynchronization for resynchronization of a primary volume to a remote secondary volume following restoration of a communications link or another event. Enhanced journal-based resynchronization involves maintaining a filled journal after the primary component system has resorted to bitmap-based journaling. Following communications-link restoration, or another event, enhanced resynchronization analyzes various values maintained by the primary component system to characterize the journaling state in order to determine whether or not to first merge the filled journal with the track-based bitmap before carrying out bit-map-based resynchronization, or to instead unspool the filled journal and transmit the unspooled WRITE requests to the second component system prior to separately carrying out bit-map-based resynchronization.

Abstract: A storage system comprises an interface capable of interconnecting a network infrastructure via a plurality of communication links. The plurality of communication links has a diversity of data-carrying capacity and performance. The storage system further comprises a controller coupled to the interface that assigns the plurality of communication links into at least one link affinity group based on performance criteria and controls link selection based on link affinity group assignment.

Abstract: Various method and system embodiments of the present invention employ enhanced journal-based resynchronization for resynchronization of a primary volume to a remote secondary volume following restoration of a communications link or another event. Enhanced journal-based resynchronization involves maintaining a filled journal after the primary component system has resorted to bitmap-based journaling. Following communications-link restoration, or another event, enhanced resynchronization analyzes various values maintained by the primary component system to characterize the journaling state in order to determine whether or not to first merge the filled journal with the track-based bitmap before carrying out bit-map-based resynchronization, or to instead unspool the filled journal and transmit the unspooled WRITE requests to the second component system prior to separately carrying out bit-map-based resynchronization.

Abstract: Described herein are exemplary storage network architectures and methods for block size allocation in copy operations. A copy operation from a first storage cell to a second storage cell is initiated. The copy operation initially utilizes a first write block size. The write block size is changed to utilize a second write block size, different from the first write block size, and a performance parameter is measured at the second write block size. The second write block size is maintained if the performance parameter exceeds a threshold.

Abstract: A method of operating a daisy-chained device-mirroring architecture (where such an architecture may include a storage node N configured to mirror data on an entity representing node N?1, a storage node N+1 daisy-chain-coupled via a first main link to, and configured to mirror data on, the node N, and a storage node N+2 daisy-chain-coupled via a second main link to, and configured to mirror data on, the node N+1, each of the nodes N and N+1 being operable under normal circumstances to forward writes received thereby to the nodes N+1 and N+2 via the first and second main links, respectively), where such a method may include: tracking, at the node N, acknowledgments by the node N+1 and by the node N+2 of writes that the node N has forwarded.

Abstract: A disaster recovery system with sequenced cascaded resynchronization comprises a plurality of data centers and a distributed control system. The individual data centers comprise a communication interface, a data storage, and a controller. The distributed control system is distributed and executable in the controllers of the plurality of data centers, and is capable of coordinating operations via the communication interfaces of the plurality of data centers to resynchronize a plurality of communication links between data center pairs of the plurality of data centers. The communication links including at least one synchronous link and at least one asynchronous link.

Abstract: A method, of controlling access to storage locations on a hard-disk-based memory device, may include: receiving an input/output (I/O) request for access to the memory device; evaluating the I/O request in terms of one or more sectors on the hard-disk-based memory device comprehended by the I/O request; and selectively granting the I/O request on a sector-specific basis.

Abstract: A data synchronization method (for a redundant data storage arrangement in which there are at least a primary storage entity and mirroring first and second remote storage entities in communication therewith, respectively, writes to the first and second remote storage entities being tracked via respective first and second sidefiles, the first and second storage entities having different levels of write-currency relative to each other) may include: comparing the first sidefile with the second sidefile; and updating writes stored at the second remote storage entity based upon the comparison of the first and second sidefiles.

Abstract: A method of operating a daisy-chained device-mirroring architecture (where such an architecture may include a storage node N configured to mirror data on an entity representing node N?1, a storage node N+1 daisy-chain-coupled via a first main link to, and configured to mirror data on, the node N, and a storage node N+2 daisy-chain-coupled via a second main link to, and configured to mirror data on, the node N+1, each of the nodes N and N+1 being operable under normal circumstances to forward writes received thereby to the nodes N+1 and N+2 via the first and second main links, respectively), where such a method may include: tracking, at the node N, acknowledgments by the node N+1 and by the node N+2 of writes that the node N has forwarded.

Abstract: Described herein are exemplary storage network architectures and methods for block size allocation in copy operations. A copy operation from a first storage cell to a second storage cell is initiated. The copy operation initially utilizes a first write block size. The write block size is changed to utilize a second write block size, different from the first write block size, and a performance parameter is measured at the second write block size. The second write block size is maintained if the performance parameter exceeds a threshold.

Abstract: A storage system comprises an interface capable of interconnecting a network infrastructure via a plurality of communication links. The plurality of communication links has a diversity of data-carrying capacity and performance. The storage system further comprises a controller coupled to the interface that assigns the plurality of communication links into at least one link affinity group based on performance criteria and controls link selection based on link affinity group assignment.

Abstract: A disaster recovery system with sequenced cascaded resynchronization comprises a plurality of data centers and a distributed control system. The individual data centers comprise a communication interface, a data storage, and a controller. The distributed control system is distributed and executable in the controllers of the plurality of data centers, and is capable of coordinating operations via the communication interfaces of the plurality of data centers to resynchronize a plurality of communication links between data center pairs of the plurality of data centers. The communication links including at least one synchronous link and at least one asynchronous link.