Resilient mediation between storage systems replicating a dataset, including: receiving, by a mediation service from one or more storage systems that synchronously replicate a dataset, a request to resolve which storage system continues to service a dataset after the request; and sending, from the mediation service to at least one of the storage systems, a positive mediation result, wherein: the storage systems that received the positive mediation result continue to process data storage requests directed to the dataset, and the storage systems that did not receive a positive mediation result from the mediation service do not continue to process data storage requests directed to the dataset.

Synchronizing metadata among storage systems synchronously replicating a dataset, where synchronizing the metadata includes: receiving, at a first storage system of the storage systems, an I/O operation directed to the dataset; determining, in dependence upon the I/O operation, a metadata update describing a mapping of segments of content to a virtual address within a storage object, wherein the storage object includes the dataset; and synchronizing metadata on a second storage system of the storage systems by sending the metadata update to the second storage system to update a metadata representation on the second storage system in accordance with the metadata update.

A method for synchronous replication of stream data includes receiving a stream of data blocks for storage at a first storage location associated with a first geographical region and at a second storage location associated with a second geographical region. The method also includes synchronously writing the stream of data blocks to the first storage location and to the second storage location. While synchronously writing the stream of data blocks, the method includes determining an unrecoverable failure at the second storage location. The method also includes determining a failure point in the writing of the stream of data blocks that demarcates data blocks that were successfully written and not successfully written to the second storage location. The method also includes synchronously writing, starting at the failure point, the stream of data blocks to the first storage location and to a third storage location associated with a third geographical region.

A clustered pair of storage systems configured for active-active bidirectional synchronous replication expose a stretched volume over paths to both storage systems. Writes to the stretched volume received at each system are replicated to the peer system. The cluster can use a time-to-live (TTL) mechanism by which a non-preferred system continuously requests a TTL grant from the preferred system to remain in the cluster. Algorithms that reduce or avoid data unavailability are described and can include assessing the health of the systems in the cluster. An unhealthy system can trigger a one-sided polarization algorithm to notify the peer system that it is polarization winner. An improved polarization technique using a witness to decide the polarization winner includes a system adding a time delay before contacting the witness if the system is unhealthy. A control component can detect an unhealthy system and disable the active-active bidirectional synchronous replication.

One or more techniques and/or computing devices are provided for replicating virtual machine disk clones. For example, a first storage controller, hosting first storage, may have a synchronous replication relationship with a second storage controller hosting second storage. A virtual machine, within the first storage, may be specified as having synchronous replication protection. Accordingly, virtual machine disk clones of a virtual machine disk of the virtual machine may be replicated from the first storage to the second storage. For example, virtual machine disk clones may be synchronous replicated, replicated by a resync process invoked by a hypervisor agent, and/or stored and replicated from a clone backup directory.

Methods, systems and computer program products for data protection across computing infrastructure comprising a plurality of geographically distant computing clusters. The geographically distant computing clusters form a distributed system comprising clusters that are assigned into availability zones. Disaster recovery policies are maintained in each of the availability zones. A first cluster detects a modification of a disaster recovery policy. The modification of the disaster recovery policy that occurred at the first cluster is to be communicated over a wide area network. Synchronization of the disaster recovery policy is accomplished by carrying out a peer-to-peer communication protocol over the wide area network. The peer-to-peer communication protocol comprises issuing a first synchronization request message from a source peer, receiving the first synchronization request message at a remote peer, and issuing a synchronization response message by the remote peer, which in turn is transmitted over the wide area network to the source peer.

A system and method for implementing optimized data replication across cloud storage nodes, the system comprising a cluster of computer system devices. The system comprises one or more memory devices and a plurality of processors. The one or more memory devices, stores a set of program modules. A processor among the plurality of processor executes the set of program modules. The set of program modules comprises an input module and a data transfer module. The input module receives a first instruction to add a first computer system device to the cluster, wherein the first computer system device comprises a first memory device. The data transfer module copies data in at least one memory device in the cluster of computer system devices, to the first memory device, based on number of computer system devices in the cluster being lesser than a predefined number.

Managing connectivity to synchronously replicated storage systems, including: identifying a plurality of storage systems across which a dataset is synchronously replicated; identifying a host that can issue I/O operations directed to the dataset; identifying a plurality of data communications paths between the host and the plurality of storage systems across which a dataset is synchronously replicated; identifying, from amongst the plurality of data communications paths between the host and the plurality of storage systems across which a dataset is synchronously replicated, one or more optimal paths; and issuing, to the host, an identification of the one or more optimal paths.

One or more techniques and/or computing devices are provided for synchronous replication. For example, synchronous replication relationships are established between a first storage object (e.g., a file, a logical unit number (LUN), a consistency group, etc.), hosted by a first storage controller, and a plurality of replication storage objects hosted by other storage controllers. In this way, a write operation to the first storage object is implemented in parallel upon the first storage object and the replication storage objects in a synchronous manner, such as using a zero-copy operation to reduce overhead otherwise introduced by performing copy operations. Reconciliation is performed in response to a failure so that the first storage object and the replication storage objects comprise consistent data. Failed write operations and replication write operations are retried, while enforcing a single write semantic. Dependent write order consistency is enforced for dependent write operations, such as overlapping write operations.

A system and method for data replication is provided. A host synchronously replicates data between a first local storage device and a second local storage device, the first local storage device and the second local storage device being coupled to the host. Data is then asynchronously replicated from the first local storage device and the second local storage device to at least one remote storage device. In an embodiment, each of the local storage devices may asynchronously replicate data to remote storage devices located at separate sites to provide four site data replication processing. The system described herein provides for advantageous and efficient swapping of control between hosts and storage devices located in different regions in response to disasters and/or other events affecting data storage in a particular region.