Abstract: An apparatus in one embodiment comprises a storage system including a plurality of storage nodes each associated with one or more storage devices. The storage system is configured to provide at least one virtual volume distributed over the storage nodes for utilization by a plurality of host devices. The storage nodes comprise respective input-output sequencers for handling input-output operations directed to the distributed virtual volume by the host devices. The input-output sequencers of the respective storage nodes are configured to interact with one another to collectively form a distributed input-output sequencer that ensures consistency across the storage nodes for the distributed virtual volume when accessed by different ones of the host devices. The storage system may comprise a multi-site storage system, with the plurality of storage nodes comprising at least a first storage node cluster at a first site and a second storage node cluster at a second site.

Abstract: An apparatus in one embodiment comprises a storage system including a plurality of storage nodes each associated with one or more storage devices. The storage system is configured to provide at least one virtual volume distributed over the storage nodes for utilization by a plurality of host devices. The storage nodes are configured to support selection between multiple operating modes for handling input-output operations directed to the distributed virtual volume by the host devices. The multiple operating modes comprise at least a cached mode of operation in which consistency across the storage nodes for the distributed virtual volume when accessed by different ones of the host devices is ensured utilizing a distributed cache coherence protocol implemented by cooperative interaction of cache controllers of respective ones of the storage nodes, and a cacheless mode of operation in which consistency is ensured without utilizing the distributed cache coherence protocol and its associated cache controllers.

Abstract: A share group for a distributed volume is separated into two non-overlapping, cluster-local SGCs (share group cliques). Each SGC has an independent local meta-directory master hosted by a computing node of the SGC cluster. Each SGC maintains an independent local directory for the distributed volume. The directory may be spread across multiple computing nodes of the SGC cluster. Changes to the distributed volume (writes) are coordinated across the pair of SGCs to provide data consistency. The coordination of these changes is conducted using relatively few inter-SGC round-trips. Read access to the distributed volume is safely conducted without inter-SGC coordination.

Abstract: A system, method, and computer product for enabling a virtual service layer to consume a first storage medium and a second storage medium and map the storage mediums as one or more virtual storage volumes; wherein the one or more virtual volumes are mirrored at a first site and a second site, mirroring of the virtual storage volumes on a distributed mirror, and enabling a distributed replication service to create a continuous data protection image of the data written to one or more virtual storage volumes.

Abstract: A system is provided for continuous protection of data and storage configuration metadata. Content protected by snapshots, for example, in connection with continuous snapshotting and/or continuous data protection, may be extended to include not only user data but further include configuration metadata of the storage management system. In particular, a user may want to rollback a storage management system to a past point due to performance or stability issues attributed to configuration changes. The system described herein enables rollback to prior states based on storage configuration metadata in addition to rollback of user data and provides for synchronization of the data and configuration metadata in connection with a rollback. The system also enables roll forward processing.

Abstract: In one aspect, a method to provide asymmetric active-active access to a first storage volume using a global cache coupled to a first and second virtual storage volumes includes replicating asynchronously the first storage volume at a first site to a second storage volume at a second site, virtualizing the first storage volume with the first virtual storage volume; and virtualizing the second storage volume with the second virtual storage volume. The first storage volume has primary storage functionality.

Abstract: In one aspect, a method includes synchronizing a second storage volume to a first storage volume by synchronizing extents according to priority based on extent activity. In another aspect, an apparatus includes electronic hardware circuitry configured to synchronize a second storage volume to a first storage volume by synchronizing extents according to priority based on extent activity. In a further aspect, an article includes a non-transitory computer-readable medium that stores computer-executable instructions. The instructions cause a machine to synchronize a second storage volume to a first storage volume by synchronizing extents according to priority based on extent activity.

Abstract: A system is provided for continuous protection of data and storage configuration metadata. Content protected by snapshots, for example, in connection with continuous snapshotting and/or continuous data protection, may be extended to include not only user data but further include configuration metadata of the storage management system. In particular, a user may want to rollback a storage management system to a past point due to performance or stability issues attributed to configuration changes. The system described herein enables rollback to prior states based on storage configuration metadata in addition to rollback of user data and provides for synchronization of the data and configuration metadata in connection with a rollback. The system also enables roll forward processing.

Abstract: In one aspect, a method to provide synchronous and asymmetric active-active-active access to a first storage volume using a global cache coupled to a first, second and third virtual storage volumes includes replicating asynchronously the first storage volume at a first site to a second storage volume at a second site and mirroring the first storage volume with a third storage volume at a third site. Either one of the first storage volume or the third storage volume has primary storage functionality. The method also includes virtualizing the first storage volume with the first virtual storage volume, virtualizing the second storage volume with the second virtual storage volume and virtualizing the third storage volume with the third virtual storage volume.

Abstract: In one aspect, a method includes continuously replicating a physical volume with no disruption to the replicating while inserting a virtualization layer which virtualizes the physical volume with a virtual volume and replicating the virtual volume instead of the physical volume after the inserting. In another aspect, an article includes a non-transitory machine-readable medium that stores executable instructions. The instructions cause a machine to continuously replicate a physical volume with no disruption to the replicating while inserting a virtualization layer which virtualizes the physical volume with a virtual volume and replicate the virtual volume instead of the physical volume after the inserting.

Abstract: A plurality of access nodes sharing access to data on a storage network implement a directory based cache ownership scheme. One node, designated as a global coordinator, maintains a directory (e.g., table or other data structure) storing information about I/O operations by the access nodes. The other nodes send requests to the global coordinator when an I/O operation is to be performed on identified data. Ownership of that data in the directory is given to the first requesting node. Ownership may transfer to another node if the directory entry is unused or quiescent. The distributed directory-based cache coherency allows for reducing bandwidth requirements between geographically separated access nodes by allowing localized (cached) access to remote data.

Abstract: A plurality of access nodes sharing access to data on a storage network implement a directory based cache ownership scheme. One node, designated as a global coordinator, maintains a directory (e.g., table or other data structure) storing information about I/O operations by the access nodes. The other nodes send requests to the global coordinator when an I/O operation is to be performed on identified data. Ownership of that data in the directory is given to the first requesting node. Ownership may transfer to another node if the directory entry is unused or quiescent. The distributed directory-based cache coherency allows for reducing bandwidth requirements between geographically separated access nodes by allowing localized (cached) access to remote data.