Abstract: A computer implemented method includes maintaining information indicative of whether a data replication relationship between a dataset associated with the local CG and a mirror copy of the dataset stored on a remote CG of a remote distributed storage system is in an in-synchronization (InSync) state or an out-of-synchronization (OOS) state, initiating a storage expansion process including a source expansion to create a new source volume as a member of the local CG and a destination expansion to create a new destination volume as a member of the remote CG, and initiating a data replication relationship expand to establish a data replication relationship for the new source volume and the new destination volume.

Abstract: A computer implemented method includes maintaining information indicative of whether a data replication relationship between a dataset associated with the local CG (CG1) and a mirror copy of the dataset stored on a remote CG (CG2) of a remote distributed storage system is in an in-synchronization (InSync) state or an out-of-synchronization (OOS) state, determining whether a CG storage expansion process is in progress, and in response to determining the OOS state and whether the primary storage site has a failure, initiating an automatic unplanned failover (AUFO) workflow without manual intervention on the original volumes in the CG1 of a first storage cluster of the primary storage site and the original volumes in the CG2 of a second storage cluster when the CG storage expansion process is in progress with a new source volume to be a member of CG1 and a new destination volume to be a member of CG2.

Abstract: 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.

Abstract: Multi-site distributed storage systems and computer-implemented methods are described for providing common snapshot retention and automatic fanout reconfiguration for an asynchronous leg after a failure event that causes a failover from a primary storage site to a secondary storage site. A computer-implemented method comprises providing an asynchronous replication relationship with an asynchronous update schedule from one or more storage objects of the first storage node to one or more replicated storage objects of the third storage node, creating a snapshot copy of the one or more storage objects of the first storage node, transferring the snapshot copy to the third storage node based on an asynchronous mirror policy, and intercepting the snapshot create operation on the primary storage site and transferring the snapshot copy to the second storage node to provide a common snapshot between the second storage node and the third storage node.

Abstract: A computer-implemented method comprises providing a synchronous replication relationship from one or more storage objects of a first storage node to one or more replicated storage objects of a second storage node, providing an asynchronous replication relationship with an asynchronous update schedule from the one or more storage objects of the first storage node to one or more replicated storage objects of the third storage node to provide a protection configuration, tracking, with the third storage node of the tertiary site, a state of the secondary storage site, automatically performing a failover from the primary storage site to the secondary storage site and activating a synchronous mirror copy for the one or more replicated storage objects of the second storage node, and automatically initiating realignment and reconfiguration of the protection configuration to the tertiary storage site based upon the state of the secondary storage site.

Abstract: Multi-site distributed storage systems and computer-implemented methods are described for improving a resumption time of input/output (I/O) operations during an automatic unplanned failover (AUFO). A computer-implemented method includes monitoring, with a second cluster, heartbeat information received at ultra-short time intervals from a first connection of one or more storage objects of the first cluster, determining, with the second cluster, whether the heartbeat information from the first connection is received during an ultra-short time interval, and intelligently routing heartbeat information from the one or more storage objects of the first cluster from the first connection to a second connection when the heartbeat information from the first connection is not received during the ultra-short time interval.

Abstract: One or more techniques and/or computing devices are provided for managing an arbitrary set of storage items using a granset. For example, a storage controller may host a plurality of storage items and/or logical unit numbers (LUNs). A subset of the storage items are grouped into a consistency group. A granset is created for tracking, managing, and/or providing access to the storage items within the consistency group. For example, the granset comprises application programming interfaces (APIs) and/or properties used to provide certain levels of access to the storage items (e.g., read access, write access, no access), redirect operations to access either data of an active file system or to a snapshot, fence certain operations (e.g., rename and delete operations), and/or other properties that apply to each storage item within the consistency group. Thus, the granset provides a persistent on-disk layout used to manage an arbitrary set of storage items.

Abstract: Multi-site distributed storage systems and computer-implemented methods are described for improving a resumption time of input/output (I/O) operations during an automatic unplanned failover (AUFO). A computer-implemented method includes determining, with a second storage cluster, whether heartbeat information from one or more storage objects of a CG of a first set of CGs is received during a time period, determining an out of sync state for a data replication relationship between the CG of the first set of CGs and a mirrored CG of a second set of CGs when the heartbeat information is not received during the time period and sending a single bulk role change call with a cluster identifier from the second cluster to an external mediator to provide a role change from follower to leader in the second set of CGs.

Abstract: One or more techniques and/or computing devices are provided for resynchronization. For example, a request may be received to create pseudo snapshots of a first consistency group, hosted by a first storage controller, and a second consistency group, hosted by a second storage controller, having a synchronous replication relationship with the first consistency group. Incoming client write requests are logged within an intercept tracking log at the first storage controller. After a first drain without hold of incoming write requests is performed, a first pseudo common snapshot of the second consistency group is created. After a second drain without hold of incoming write operations is performed, a second pseudo common snapshot of the first consistency group and the intercept tracking log is created. The pseudo snapshots and the intercept tracking log (e.g., indicating a delta between the pseudo snapshots) are used to resynchronize the first and second consistency groups.

Abstract: One or more techniques and/or computing devices are provided for implementing synchronous replication. For example, a synchronous replication relationship may be established between a first storage controller hosting local storage and a second storage controller hosting remote storage (e.g., replication may be specified at a file, logical unit number (LUN), or any other level of granularity). Data operations and offloaded operations may be implemented in parallel upon the local storage and the remote storage. Error handling operations may be implemented upon the local storage and implement in parallel as a best effort on the remote storage, and a reconciliation may be performed to identify any data divergence from the best effort parallel implementation. Storage area network (SAN) operations may be implemented upon the local storage, and upon local completion may be remotely implemented upon the remote storage.

Abstract: Multi-site distributed storage systems and computer-implemented methods are described for improving a resumption time of input/output (I/O) operations during a common snapshot procedure for storage objects. A computer-implemented method includes initiating a snapshot multi create operation to selectively form a batch of first and second synchronous replicated datasets that belong to a first group of storage disks at the primary storage site and corresponding second group of storage disks at the secondary storage site, performing a batch snapshot create operation on the primary storage site by executing snapshots of storage objects on the primary storage site of the batch of first and second synchronous replicated datasets in parallel multiple threads to effectively utilize processing resources on the primary storage site, and initiating an independent workflow and state machine for each storage object of the batch of first and second synchronous replicated datasets.

Abstract: Multi-site distributed storage systems and computer-implemented methods are described for providing common snapshot retention and automatic fanout reconfiguration for an asynchronous leg after a failure event that causes a failover from a primary storage site to a secondary storage site. A computer-implemented method comprises providing an asynchronous replication relationship with an asynchronous update schedule from one or more storage objects of the first storage node to one or more replicated storage objects of the third storage node, creating a snapshot copy of the one or more storage objects of the first storage node, transferring the snapshot copy to the third storage node based on an asynchronous mirror policy, and intercepting the snapshot create operation on the primary storage site and transferring the snapshot copy to the second storage node to provide a common snapshot between the second storage node and the third storage node.

Abstract: A computer-implemented method comprises providing a synchronous replication relationship from one or more storage objects of a first storage node to one or more replicated storage objects of a second storage node, providing an asynchronous replication relationship with an asynchronous update schedule from the one or more storage objects of the first storage node to one or more replicated storage objects of the third storage node to provide a protection configuration, tracking, with the third storage node of the tertiary site, a state of the secondary storage site, automatically performing a failover from the primary storage site to the secondary storage site and activating a synchronous mirror copy for the one or more replicated storage objects of the second storage node, and automatically initiating realignment and reconfiguration of the protection configuration to the tertiary storage site based upon the state of the secondary storage site.

Abstract: Multi-site distributed storage systems and computer-implemented methods are described for improving a resumption time of input/output (I/O) operations during an automatic unplanned failover (AUFO). A computer-implemented method includes determining, with a second storage cluster, whether heartbeat information from one or more storage objects of a CG of a first set of CGs is received during a time period, determining an out of sync state for a data replication relationship between the CG of the first set of CGs and a mirrored CG of a second set of CGs when the heartbeat information is not received during the time period and sending a single bulk role change call with a cluster identifier from the second cluster to an external mediator to provide a role change from follower to leader in the second set of CGs.

Abstract: Systems and methods are provided for bringing a volume of a consistency group (CG) into an in-synchronization (InSync) state while other volumes of the CG remain in the InSync state. According to an example, in order to support recovery from disruptive events in a manner that ensures a zero recovery point objective (RPO) guarantee and insulates an application making use of the CG from adverse impacts, responsive to a triggering event, a Fast Resync process may first be attempted to promptly bring an affected volume back into an in-synchronization (InSync) state from an out of synchronization (OOS) state while allowing other members of the CG to remain in the InSync state. Should the Fast resync process be unsuccessful in bringing the volume back into the InSync state within a predetermined or configurable time threshold, then a second type of resynchronization process may be employed at the CG level.

Abstract: Systems and methods for reducing delays between the time at which a need for a resynchronization of data replication between a volume of a local CG and its peer volume of a remote CG is detected and the time at which the resynchronization is triggered (Reseed Time Period) are provided. According to an example, information indicative of the direction of data replication between the volume and the peer volume is maintained within a cache of a node. Responsive to a disruptive operation (e.g., relocation of the volume from a first node to a second node), the Reseed Time Period is lessened by proactively adding a passive cache entry to a cache within the second node at the time the CG relationship is created when the second node represents an HA partner of the first node and prior to the volume coming online when the second node represents a non-HA partner.

Abstract: Systems and methods include negotiating a primary bias state for primary and secondary storage sites when a mediator is temporarily unavailable for a multi-site distributed storage system. In one example, a computer-implemented method comprises detecting, with the primary storage site having a primary storage cluster, a temporary loss of connectivity to a mediator or a failure of the mediator. The computer-implemented method includes negotiating the primary bias state and setting the primary bias state on a secondary storage cluster of the secondary storage site when the secondary storage cluster detects a temporary loss of connectivity to the mediator, determining whether the primary storage cluster receives a confirmation of the secondary storage cluster setting the primary bias state, and setting the primary bias state on the primary storage cluster when the primary storage cluster receives the confirmation.

Abstract: According to an example, a computer-implemented method comprises initiating a first process for atomically setting the primary bias state with a first node of a primary storage cluster of a multi-site distributed storage system due to a temporary loss of connectivity to a mediator or a temporary mediator failure, releasing an atomic lock for the first process on the first node of the primary storage cluster, sending the first process and an associated first generation indicator to a first node of a secondary storage cluster of the multi-site distributed storage system to handle the first process for setting the primary bias state, and initiating a second process for atomically clearing a primary bias state with the first node or any node of the primary storage cluster based on detecting a connection to the mediator or detecting that the mediator is available.

Abstract: Multi-site distributed storage systems and computer-implemented methods are described for improving a resumption time for processing of input/output (I/O) operations during an automatic unplanned failover (AUFO). A first storage cluster includes a first set of consistency groups (CGs) and a second storage cluster includes a second mirrored set of CGs. A computer-implemented method includes prefetching, with a user space of the second storage cluster, configuration information from a replicated database prior to starting the AUFO workflow, sending the configuration information to a kernel space of the second storage cluster on a per CG level while queuing the AUFO workflow, and determining if any in progress workflows conflict with the AUFO workflow.

Abstract: 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.