A technique replicates an index of an operations log (oplog) from a primary node to a secondary node of a cluster in the event of a failure of the primary node. The oplog functions as a staging area to coalesce random write operations directed to a virtual disk (vdisk) stored on a backend storage tier organized as an extent store. The oplog temporarily caches data associated with the random write operations (i.e., write data) as well as metadata describing the write data. The metadata includes descriptors to the write data corresponding to virtual address regions, i.e., offset ranges, of the vdisk and are used to identify the offset ranges of write data for the vdisk that are cached in the oplog. To facilitate fast lookup operations of the offset ranges when determining whether write data io is cached in the oplog, an oplog index provides a state of the latest data for offset ranges of the vdisk. The technique enables fast failover of metadata used to construct the oplog index in memory of a node, such as the secondary node, without downtime or significant metadata replay.

The disclosure herein describes placing delta components of a base component in target fault domains. One or more delta components are generated. When a first fault domain that lacks a sibling component of the base component is identified, the first fault domain is selected as a single delta target fault domain and a single delta component is placed on the single delta target fault domain. When a second fault domain that includes a first sibling component of the base component is identified and a third fault domain that includes a second sibling component of the base component is identified, the second fault domain and the third fault domain are selected as a first double delta target fault domain and a second double delta target fault domain, and a first double delta component and a second double delta component are placed on the first and second double delta target fault domains.

Replicating multiple storage systems utilizing coordinated snapshots, including identifying a replica dataset stored across two or more target storage systems, wherein the replica dataset is a replication target for a source dataset stored across two or more source storage systems; identifying two or more local replicated checkpoints that are replicated from the two or more source storage systems to the two or more target storage systems, wherein two or more local source checkpoints for the two or more local replicated checkpoints are associated with a coordinated source checkpoint for the source dataset; and determining, based on the two or more local replicated checkpoints, a coordinated target checkpoint for the replica dataset.

A data replication method includes obtaining differential data information corresponding to differential data, where the differential data information includes a storage address of the differential data, and a determining value of the differential data. The data replication method comprises replicating the differential data from the primary volume to the secondary volume according to the storage address of the differential data that is located in the primary volume when the determining value is not less than a preset threshold. The data replication method comprises taking a snapshot for the primary volume when the determining value is less than the preset threshold and replicating the differential data to the secondary volume.

In certain systems disclosed herein, a distributed data monitoring and management system is provided that can replicate a distributed storage environment. The distributed data monitoring and management system can intelligently and automatically configure data access nodes to form a structure that matches the distributed storage environment. By matching the structure of the distributed storage environment, the distributed structure of the data may be maintained, enabling the data to be backed up from and/or restored to the distributed storage environment and/or migrated to another distributed storage environment without altering the distribution of the data. Further, embodiments herein enable the monitoring of nodes within the system and transfer of data from a non-distributed environment to a distributed storage environment. Thus, in some cases, an entity can migrate data from a local storage structure to a network-based distributed storage structure.

A method for use in a storage system disclosed, comprising: transitioning the storage system into a first state, the first state including a state in which a source system performs synchronous replication to a target system; detecting a first event while the source system is in the first state; in response to the first event, transitioning the storage system from the first state into a second state, the second state being a state in which the source system performs asynchronous replication; detecting a second event while the storage system is in the second state, transitioning the source system from the second state into a third state, the third state including a state in which the source system performs both synchronous replication and asynchronous replication.

Data loss thresholds are enforced when performing updates to mirrored data sets. When an update is received for a data set that is mirrored to other copies of the data set, an evaluation of the difference between the data set and the other copies of the data set may be performed. If the evaluation determines that the difference fails to satisfy a threshold for acceptable data loss at the other copies upon a failure of the data set, a data loss mitigation action may be applied to performance of the update until the difference satisfies the threshold.

A secondary location is configured as a recovery service for a primary location of the service. The secondary location is maintained in a warm state that is configured to replace the primary location in a case of a failover. During normal operation, the secondary location is automatically updated to reflect a current state of the primary location that is actively servicing user load. Content changes to the primary location are automatically reflected to the secondary location. System changes applied to the primary location are automatically applied to the secondary location. For example, removing/adding machines, updating machine/role assignments, removing adding/database are automatically applied to the secondary location such that the secondary location substantially mirrors the primary location. After a failover to the secondary location, the secondary location becomes the primary location and begins to actively service the user load.

An apparatus, system, and method are disclosed that service SCSI commands, including SCSI PGR commands in the standby node of a storage system that operates in an Asymmetric Logic Unit Access (ALUA) mode. The apparatus, system, and method service SCSI PGR commands without maintaining peer/proxy port information. The apparatus, system, and method service SCSI commands by forwarding/proxying commands between the active node and standby node, in both directions and use a modified command descriptor block (MCDB) message to conduct the communications between the nodes.

Metadata logic switches selection of a metadata track from multiple available metadata tracks in a volatile cache to fill the selected metadata track in a metadata track selection interval with metadata entries as source tracks of a source volume are copied to a backup volume of a copy relationship. Destage logic destages to storage a deselected metadata track containing metadata entries generated in a prior metadata track selection interval, while the metadata logic continues to generate and fill additional metadata entries in the selected metadata track in a concurrent metadata track selection interval. Other features and aspects may be realized, depending upon the particular application.