One or more techniques and/or systems are provided for dynamic mirroring. A first storage node and the second storage node within a first storage cluster may locally mirror data between one another based upon a local failover partnership. The first storage node and a third storage node within a second storage cluster may remotely mirror data between one another based upon a primary disaster recovery partnership. If the third storage node fails, then the first storage node may remotely mirror data to a fourth storage node within the second storage cluster based upon an auxiliary disaster recovery partnership. In this way, data loss protection for the first storage node may be improved, such that the fourth storage node provide clients with access to mirrored data from the first storage node in the event the second storage node and/or the third storage node are unavailable when the first storage node fails.

Customers of shared resources in a multi-tenant environment can modify operational parameters of electronic resources. A customer can be provisioned a data volume of a specified size, storage type (e.g., hard disk drive or solid state device), committed rate of input/output operations per second, and/or geographical location, for example. The customer can subsequently modify any such operational parameters by submitting an appropriate request, or the operational parameters can be adjusted automatically based on any of a number of criteria. Data volumes for the customer can be migrated, split, or combined in order to provide the shared resources in accordance with the modified operational parameters.

A storage system has priority queues for real time-class file system messaging and backup-class file system messaging. The storage system includes servers, coupled as a storage cluster, storage devices and a network coupling the servers and the storage devices. The servers have priority queues. The servers operate the priority queues for messaging from the servers to the storage devices via the network in accordance with a real time-class file system and a backup-class file system. A first subset of the priority queues has higher priority on the network for real time-class file system messaging of at least one type. A second subset of the priority queues has lower priority on the network for backup-class file system messaging of at least one type.

Techniques, which provide visual representations, involve displaying, in a first display area, a plurality of first visual representations indicating a plurality of storage nodes in a storage system, the plurality of storage nodes in the storage system having data replication relations, and the data replication relations including: replication of first data at a first storage node to one or more second storage nodes, and/or replication of second data at one or more second storage nodes to the first storage node. The techniques further involve displaying, in the first display area, a plurality of second visual representations indicating a plurality of data replication relations between the plurality of storage nodes. Accordingly, respective storage nodes in the storage system in a topology view can be visualized, and data replication relations between the respective storage nodes can be clearly described.

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.

Configuration and replication can be managed across multiple sites for datacenter volumes. A visual representation of a current configuration for a first of a plurality of replication techniques can be conveyed for display on a display device. Changes can be made to the current configuration, producing a future configuration. The future configuration can be analyzed for replication errors, and an updated visual representation can be produced that identified discovered replication errors and highlights differences between the current configuration and the future configuration. The updated visual representation can be conveyed, for display on a display device.

Ensuring resiliency to storage device failures in a storage system, including: determining a number of storage device failures within a particular write group that are to be tolerated by the storage system; for a plurality of datasets stored within the storage system, writing each dataset to at least a predetermined number of storage devices within the particular write group, wherein the predetermined number of storage devices is greater than the number of storage device failures within the particular write group that are to be tolerated by the storage system; and responsive to recovering from a system interruption: determining a number of readable storage devices that contain a copy of the dataset; and if the number of readable storage devices that contain a copy of the dataset is not greater than the number of failures that are to be tolerated, writing the dataset to one or more additional storage devices.

A method for improving reliability of a storage system and a related apparatus, where the storage system includes a first control device and a second control device. The method includes receiving, by a target controller, a write request, where the write request includes to-be-written data, and the target controller belongs to the first control device; writing, by the target controller, the to-be-written data into a memory of the target controller; and writing, by the target controller, the to-be-written data into a memory of a mirror controller of the target controller, where at least one mirror controller belongs to the second control device.

Withdrawal of a point-in-time snap copy relationship or a portion of such a relationship, is managed in a manner which can obviate disruption of consistency groups due to the withdrawal. If the withdrawal request is directed to a subrange of the original snap copy relationship, the snap copy relationship is split by creating one or more point-in-time snap copy relationships over one or more subranges of tracks of the snap copy source. A determination is made as to whether to delay execution of the withdrawal request to temporarily preserve data of the withdrawal range. Disruptions to completion of consistency groups may be avoided by selectively delaying the withdrawal of a snap copy relationship corresponding to the withdrawal subrange. In so far as the host is involved, a host may treat the withdrawal request as immediately granted without delay. Other aspects may be realized, depending upon the particular application.

The disclosed technology generally describes a preliminary (e.g., triple mirroring) data protection scheme that operates by writing data as redundant (e.g., three) composite copies made up of copies of data fragments to different nodes of a data storage system. The data fragments are distributed such that any two nodes can fail yet a complete set of data remains among the remaining data fragments. Later, erasure encoding creates redundant coding fragments that are written to the nodes of a data storage system in a distributed manner along with one copy of the data fragments, such that any two nodes can fail but the complete data can still be recovered. Redundant data fragments are then deleted.